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Observations on Davainea Proglottina in the Domestic Fowl—with a Note on Amoebotaenia Sphenoides v. Linstow
OBSE RVATIO~ S
0~
D OME T IC FOWL
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OBSERVATIONS ON DAVAINEA PROGLOTTINA IN THE DOMESTIC FOWL- WITH A NOTE ON AMOEBOTAENIA SPHENOIDES v. LINSTOW. By
ORMA
BISSET, M.R.C.V.S.,
.<,- ;ziUr T'ctcri11nry Ad1 •isory Officer, Uui< ·ersitv College of. 'o uth W ales,
Cardiff.
n.
ALTHO CC II proglott-ina has rece ived perhaps as much attention an tl im·cs tiga tion- parti cul arly from Continental wo rkers- as any , ,rher wor m ; and indeed is refe rred to bv tile;; as " one of th e few w•,rn h ,,·h ich is compara ti vely well known from a scientific poin t of vit·w ,·· , ·et , with th e excep tion of the work of :Yieggitt, little, if any, literature can be found on th e occurrence and effects of this minute Ch t odc of birds in thi s country . It is. therefore, pro posed to d escri be in ·de ta il an outbreak of d i ~case in a fl oc k of fowl s. in wh ic h two different t ypes of parasites, Yiz., cestode a nd protozoan, co mbined their attacks, the ces tode being LJ. proglottina , a nd th e protozoan Fimeria a1•i11 111. . ince that outhreak whi ch was th e lirs t occasion on which D. proglottina was dis' "'·ered b~ · the writer , and which occurred in 1924. the parasites have bt:en encoun tered in an ever-increasing number of cases from different diq rict s in C lamorgan a nd Monmou thshire. Tt ma\· well be that , since th e outbreak in q uestion , s pecial attention has been directed t " th t; presence or a bsence o f D . proglottiua . which. owing to it s minute ;;izc . is ca,-ih' o\·e rl ooked , especiall y wh en unexpec ted. The writer ma \ · as well confess at once th at llC' \\'as taken b\· s urprise in the fn·;; r instan ce, as will ap pear later. Th e fact rema in ·, howe,·e r . t ha t in the ca::e of e \·ery fow l on \\ hich a post-m ortem examinat ion has been conducted , a thorough {> \a mination fo r pa rasites, both mac rosco!)iC and microscopic, external ;,nd intern al. h as im·a ri ab ly been made a~ a rou tine procedure, and u nt il th e outbreak about to be desc ribed , D. proglottina had not been (,] •:::en ·ecl. :-;in ce that time . as mentioned a bove. the parasites or th eir ]"•~ terior seg ment s ha,·e been fou nd . in excreta from li ve fow ls, a nd '•n posl-morlelll ex a mi na tion in a rapidl y increasing number o f instances, in .til of \\·hi ch the paras ites h a ,·e been quite ob,·ious to the naked eye, ' " m uch so th at it is d ifficu lt to imagine tha the~· co uld ever ha,·e 1Jn· n ()\·erlooked .
.\ consi derable number of fow ls wh ich had ceased laying, lost ,-,.. nd iti on , a nd become ge nera l!\· unthrifty, and in the excre ta of which nu m erotb posterior segmen ts have beeri fo und, h a ,·e been treated ln the int rodu cti on in to the crop of a teaspoonful of turpentine, the
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fowls h aving previously been fasted a nd dosed with Epsom salts. These fowls have, in every case, after a second dose of salts given four hours after the turpentine, expelled the parasites in numbers varying from 100 to 300 and in a short time h ave recommenced laying a nd put on fl esh, the average time taken for recovery being betweeJ1 two and three weeks. It would appear, therefore , that the cestodes exercise rather more of a detrimental effect on their hosts than has hitherto been supposed. The outbreak in question occurred in a fl ock of White W yandottes, numbering 30 in all. The fowl s had all been h atched on the premises, and none h ad been introduced from ex ternal sources. They were of various ages, b ut those which showed signs of illness were all aged between two and three months. The symptoms commenced to appear when the birds were on e month old previous to which time the whole flock was apparently in perfect h ealth. Before the writer was consulted two " diagnoses " of the condition had been obtained by the owner from different sources. The first blamed the feeding and ascribed t he disease, which, however, wa not defined , to th e eating of decayed wind-fallen apples. The second reported the cause of th e trouble to be coccidiosis. The owner then referred to the writer who visited th e premises a nd examined the flock and its surroundings. Twenty-three birds were left , but no isola tion had been practised . Seven older fowls appeared healthy, but 16 birds of eight to ten weeks old were showi ng symptoms of disease . They all had the run of a small orcha rd, about one-sixth of an acre in extent. The houses appeared clean and well looked aft er. Th e owner described the symptoms of those fowls which had died as dullness, p rog ressive and rather rapid emaciation, paleness of the comb a nd skin of the h ead and a tendenC\' to seek seclusion and to stand for lon g p eriods in a " hunched-up " posi tion. Four birds ou t of seven h ad " died m convulsions." An examination of the 1(i affected birds conlirmed the owner 's description . In the h ouses they stood in the " hunched-up " position in attitudes varying from medi tative to misera ble, n ow and again closing the eyes and allowi ng th emselves to be pushed aside by the a ppa rently unaffected birds. The " ruffled feathers" so evident in tex t-book description s of p oultry diseases were not noticeable. The tail was drooped and the head sunk between t he sh oulders. The comb, wattles and skin of the head were mark edly amemic- in most cases quite blanched with no sign of pink colour whatever . Th e
OBSERVATION S ON DOMESTIC FOWL
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d roppings were watery at one evacua tion , apparently normal a t ano ther, a nd slimy and of a reddish colour at yet anoth er. There was, however, no evidence of true white diarrhcea such as is associated with coccidiosis in young chicks. The birds were very emaciated and extraordinarily light wh en handled . On bei ng put into the run they a ttempted to resume their somn olent attitude, but on being forced to move they showed distinct weakness of t he legs. Once forcibly livened up and on food b eing offered . th ey ate Yor aciously for a short time and then relapsed into their fo rm er comatose state. The eyes when opened w ere quite bright , but somewhat" sunken. The owner m entioned the fact of the appetite being maintained a nd , indeed somewhat increased, but stated that fo r abo ut 24 hours before death all appetite was lost. Bearing in mind both previous reports on the cause of the disease, which had , naturally, somewh at confused the owner, the writer by a little cross-examination elicited the following facts: (1) Thi s was the first outbreak of disease of any kind on th ose premises. (2) No birds h ad been introduced from external so urces. (3) The fowl s had always been fed in the same way a nd h ad always at th e proper season had access to the wind-fallen apples, th e orcha rd being their run .
(4) Dia rrhcea had been noti ced in two in stances only out of the 23 affected. The se ven apparently health y birds were immediately isolated and permission wa s g ran ted for the slaughter and post-mortem e xamination of what appeared to be th e worst case, which was brought to the laboratory for th e purpose. Th e fowl was ex trem ely emaciated a nd showed a ll the above-mention ed symptoms, including bl anching of the comb a nd skin of th e head. Post ~ Mortem.
Th e internal organs at fi rst glance appeared normal except t hat the gall bladder was en larged, and that a ll fat seemed to have dis<~ppeared. Th e li ver was p erfectly clean and normal in colou r an d the c
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greenish coloured fc:eces. The duodenal wall were considerably thick ened and th e mucous membrane was dotted wi th pe techial 11c:emorrh ages which also , though to a less degree, extended throughout the small intes tine. None were present in the cceca. Examin ation ·of wet films of the intes tinal contents revealed coccidial oocysts. These were fairly numerou s. but not nearly to such an extent as one may ·ee in a t ypical ca e of coccidiosis in a chick a fort nigh t oldwhere th e li \'er and cceca a re typically affected . While the wri ter was examining th e film from the duode nal contents th ere was a swirl at th e edge of the field , a nd into it ca me .a large body p ossessing amazing contractile p owers and p rog ressing by contracting itself in to a ball , followed by Yigorous extension. T he best description of its movement one ca n think of is to say that it poured itself along. T he body appeared to ha ve neither head nor tail, but it proceed ed always so to speak " head ·· fi rst, i. e., it had to t urn round to move in a reverse direction . It was full of minute ovoid bodies. Following it came two others, one of which . however, had a ttached to the " anterior " end two smaller bodies. On fu rther ex amin a ti on of the tilm numerous oth ers were found. The duoden al muco us membrane was th en exami ned by means of a han d lens when very numerous elongated oval bodies could be seen apparently a ttached to the mucous m embra ne and s~a nding up on end in the muc us which was adherent thereto . .\ scraping from the mucous m embra ne was examined micro. copically. About a dozen minute tapeworms were found in t he scraping, some con isting of fi ve segments and othe rs of four. T he large " b odies" descri bed above were the posterior segmen ts which had become detached . These tapeworms, which were fo und to be Davainea proglottinn, will be described in detail belo\1'. , II the parasites, or to be more exact, th eir posterior egmen ts, were very active . Th e hao morrhages in the intestinal wall appeared through the h and lens as if they h ad been made with a camel h ai r brush, or as if the ces todes h ad scratched the mucous membran e wi th th eir hooks. A before menti oned, th ey were most numerous in the d uodenum , .but were eviden t th e whole length of the small intes tin e. Th e paras ite also were less numero us in the la rge intestin e and in th e cceca none were fo und. Th e cceca a nd their contents, it should be emph asised, were macroscopical!\· nonn al in every way, i.e. , the wall;; we re not thickened , nor were the contents cheesy or inspissated though oocys ts were fo und therein. Co mpl ete five-segmen ted or four- egmented worms we re found .only in t h e d uoden um and mostly in the branch connected \\'i th the
OB ERVATION S
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DOMESTIC FOWL
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gizzard. Further down th e intestin e three, two and one segment s were fou nd , but no heads. Wh ere a ny da rk coloured intestin al contents were present the la rge posterior segments cou ld be di stinguished with th e na ked eye against th e dark background a nd t heir contractions co uld also be observed with out th e aid of a lens. T hev were much more diffi cult to see again st th e actual mucous membrane ?\ ext day word was received that two other bircl s had d ied , one " in convulsions." t hi s in spite of the fact th at t he fow l examined tlw day b efore h ad been carefull y chosen as showing most obvious symptoms of illn ess. T hese two fowls were brought to t he labo ra tory and ex amin ed. Th ey were also emacia ted , amem ic, and ex tremely light. The crops were 1uite empty . A in the f1rst case, a t fi rst glance the in tern al organs appeared normal ex cept for enl argement of the gall bladder a nd absence of fat ; b ut in the case of the one which was reporterl to h ave died in convulsion s th e intestin e, besides showin g t he red and purpl e spots on the peritoneal surface was of a rosy pink colou r t h ro ughout . On opening it the m ucous m embrane of th e duodenum presented an appalling condition due to the hcemorrh ages. One p a tch in size about } in . by t in . near the gizzard was almost black , while the appearance of the res t of the mucous membrane of the sma ll intestine could b est be descri bed as clark purple reel with minute white points, t hose b eing the only parts left of the norm al mucous membra ne. The co ntents con sisted of tenacious brown ish or p inkish mucus in which we re clots of blood and lively posterior segments of D. proglottina. Through the mucus t he hcemorrh ages co uld be seen. The mucoid in testinal contents were lightly scraped away wh en it was noticed that the hcemorrh agic mucous membrane presented a rather cloud \· a ppearance as though a fi lm were over it. Ex amin ation with a hand lens showed it to b e ·o th ickly studded with the ces todes that the po in t of a p in could barely be placed between th em. Th ey reminded o ne forcibly of t he papilla: of th e mucous membrane of the rumen of t he ox. As b efore, t he worms appea red to be s tand ing on their heads, t!I posterior segments bein g a ll that could be seen , although numerou s pos t ' rior segm ents and com plet e wom1s were ly ing longitudinally and t ransversely on to p of the other . So num erou were the parasites that it was practically im possible to count them. This "mass form ation "ex tended for a lmost h alf th e length oi the intes tinal t ract and it is noteworthy th at the hcemorrh ages were less num erous in the latter half, although in this case th ey were found t hroughout the whol e length including the cceca. Segments of worms were a lso found throughout th e comple te intestin al tract except the cceca, but
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no heads were found posterior to the end of the extraordin ary m assed formation. Again there were no obvious macroscopic signs of coccidiosis so far as regards the appearance of the li ver and cceca. With the exception of the few isolated hcemorrhages in the latter, they appeared quite normal in every other respect . Coccidia were found, however, .in the intestinal contents, but as before they did not appear to b e p resent in excessive numbers. The findings on opening the intestines of the other fowl corresponded with those noted in the first specimen ; hcemorrh ages a nd worms being plentiful and oocysts also being found . :\ visit was immediately paid to the affected premises. Exhaustive search was made for slugs (Limax) without result. No marshy land or streams were in the immediate vicinity. It should be noted that no trace of slugs was found in any of the birds examined. Three of the remaining birds which seemerl most seriously affected were brought to the laboratory. Two were killed a nd examin ed with the same result- abundance of hcemorrhages and cestodes, Coccidia present , bi.tt liver and cceca and ccecal contents normal in appearance. The third fowl was kept under observation in a special cage so constructed th a t the droppings could be easily collected for ex~ min a ti on . (It m ay be mentioned here tha t treatment was sugges ted and drugs were actually procured , but it was found a few days later that the owner had destroyed the remaining birds and burnt the carcasses.) • The droppings of the last-mentioned fowl varied in consistency. Some evacua tions appeared quite normal in consistency , but were partly dark green and partly brown or reddish brown. Others were softer, but all were formed to a certain extent, i.e., there was no true diarrhcea. Numerous vigorously moving posterior segments from .;;, in. up to almost ~ in. in length could be easily seen on th e surface of the droppings. Some were globular like pin heads, a nd about the same size. The ma jority were not "crawling about," but were stretching out their a nterior portions from the surface of the exc reta .and waving to an d fro very much like a cobra preparing to strike. vVithin a few minutes, however, they left the excreta a nd proceeded to "crawl" away from it. 'Within an hour, on a large tray on a bench top, without the assistance of any additional m oisture several of these segments had reached a dis tance of two feet from th e excreta. This fact was noted from the examination of subsequent droppings, but from the surface of the first evacuation after the fowl had b een placed in the cage 65 segments were easily picked off. The droppings were then teased apart , a nd it was found that the dark green portion was normal in consistency throughout, while the brownish-red portion consisted of blood-stained extremely tenacious mucus with here and
OBSERVA TIO~ S 0:\ DOMESTI C FOWL
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1hcre blood clots and lum p~ of a clear _ye llowish jelly. Pos terior :'l!g men ts were fo un d in bo th t he a pparentlv normal a nd the mucoid l<•.: cret J. which were well teased apa rt a nd was hed with wa ter. In all l 14 segments were fo und in the one evacuatio n . .-\n hour later a nother evac ua tion was passed a nd exa mined in a o'im il a r manner, but onl y 27 segmen ts were picked out. The droppings th is tim e were entirely reddish-bro wn mucoid materi al, but were m ore :fluid a nd not so well formed as previously. F ro m a t hird evac ua tion a bout an hour later bu t fo ur segm ents were removed. As this fowl ,,-as ke pt as a so urce of sup ply of t he para~ i tes no treatment was .a ttem pted , and it is rem a rkable th at a lth ough it was one of the m os t ma rkedll· affected wh en removed from t he tloc k a nd should by a ll .a ppearan ces have di ed within a few clays , yet not only did it sur vive fn r a lm ost six wee ks, but it also los t the somn olent appearance to a certain ex tent and a slight trace of colour began to return to th e comb . At the end of th a t t ime it was kill ed a nd a!t ho ugh coccidia, cestocles a nd hcemorrh ages were found as b efo re, all three were present in a Jess deg ree th an in the other fi ve fowl s examined , as th ough th e nat ura l resista nce of the body had been success ful to a certa in point in dealing with bo th ty pes of pa rasites alrcach · present when once the host was removed from the risk of fresh infec ti on. Th ere is probab ly little d oubt th a t th e ac tu a l cause of death was coccidiosis, alth ough the absence of lesions on the li ver and a lso of the enla rged cceca with th eir cheesy contents is ra th er rema rka ble. It is, of course, well kn own th a t a condition of h
As descriptions of D . proglottina have a !ready been publi shed , a nd as the observa tions of th e writer a gree with th em in prac t ica ll y all respects, it wi ll suffi ce he re to quote the description given by Stiles
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(Tap eworms of :Poultry , BU LL 12, U .S. Dept. of Agric. Bureau of Animal Industry, p . 47) :"Diagnosis: 0 · 5 mm. to 1 · 55 mm . long b y 0 ·18 mm. to 0.50 m m. broad. H ead club shaped to q uadrangular, 140,u. to 250,u. long by l35t-t to 200,u. broad, rather rounded in front and slightl y constricted in back to form neck (10 ,u. broad) ; apex a rmed with retractile hemispherical rostellum 55,u. in its a ntero-pos terior diameter and 601'- to 85,u. in its lateral diameter ; base of rostellum armed with about 80-95 h ooklets measuring 6 · 5,u. to 7 · 5,u. Suckers circular, small (251'- to 35,u.) armed with a single row of hooklets (6t-t), with rather large, bilohed base. Strobila composed of two to five segments , first segment only about 56!'- long, the following segments increasing in length a nd width. Genital pores irregularly alternate, situated at the anterior angle. The second segment possesses well-developed male organs and th e anlagen of female organs. In the third segment the testicles a re a trophied , the female organs (median posterior vitell arium , two ovaries, recept. sem. vagin a) well de veloped, but no uterus present. In th e fo urth segment all the genital glands are atrophied, and the segment is fill ed with numerous isolated eggs (not in egg capsules), ova 35p. to 401-'; hooks of oncosphere 101'to 111-', The segments have a great tendency to separate more or less completely ; the last segment, after separating, remains in the intestine and grows to 2 mm. long by 1 · 25 mm. broad (la rger than the entire worm)." To the above description the following obse rvations on th e worms found in the foregoing cases may be added :LENGTH.- Several complete worm s were found to b e 2 mm. in length. NUMBER Of SEGMENTS.-No two-segmen ted worms were foun d. The average number was five , but fours were also common. This applies to the obviously complete worm . Numerous three-segmented worms were observed from whi ch the posterior segment had apparently just separated , but as t hese might h ave been accidentally broken they were not considered. Th e total length of the cestode depends , of course, on the number a nd size of the segments, particularly the size of the posterior segment. SucKERS.- The suckers are four in number and agree in dimensions with Stiles 's figures, but the booklets urrounding them are i n triplicate a nd not in a single row, as they are found round the b ase of the rostellum. Th e hooklets a re shaped like a ha mmer. THE PosTERIOR SEGIIIENT.- This segment appears to b e the most important part of the whole parasite. Indeed , it is not exaggerating
OBSERVATIONS ON DOMESTI
FOWL
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n ' n · much t o say th a t it a ppears to contain the " intelligence" as
wel l a the mo tive powe r. The penultimate seg ment shows feebll' contract ile powers, but in those a nterior to it no movement whatever could be observed. They a ppear to be pushed this way and that at the " will " of the posterior . egment , whic h shows a mazing energy , becoming altern a tely globul a r and then linear, as it pours itself along, pushing its unresist in g " passengers" in front of it , as it would do when free in t he lumen of the in tes tin e. The pos terior egment is co mpl cte lv fill ed with eggs contai nin g oncos ph eres. Separation of Posterior Segment.
Th e se pa rati on of the post eri or segment from the res t of th e strobila hy no mea ns a simpl e decidu ous process like a d ead lea f falling fro m a branch, and it is interes ting to wa tch under the micro cope the casting off of the posterio r segment or rather the casting off of the an terior segments by the posterior , for that appea rs to be a more accura te de. cription of th e process. IS
lt mus t be borne in mind that the descripti on appli es to a parasite examined Sltper vitrmn, i. e ., on a slide.
As be fore mentioned , th e penultima t e segment shows compa ra tively feeble co ntractile powers during progression. When the time h as come for the posteri or segmen t to se para te, the other segments incl uding th e p enultimate become 4u it e immobile. The p ost eri or seg ment then in creases its contractions, and , as it p ushes forward , lirs t with long s teady s trokes, a nd th en wi t h li ttle jerks, as if it were indeed senti e nt , the a n terior segments fa ll slowly to one side. The sticky tenacious mucus appa rentl y he lps to so me extent in the procedure by re taining the a nteri or segments , while the p os terior ,.;eg mcn t t ea rs itself away . .\ fter a littl e ti me the posterior seg ment ,.;eem;; to become tired , th e contractions become slower, a nd ti.nally cease for a few seconds. Then with redoubl ed force they recommencelong steady st rokes , a ltern ated with jerks, the anterior egmen ts falling more a nd mo re t o the side. 1t would almost appear at times as if t he po terior segment were shaki ng its " head" like a terrier with a rat , as if in annoyance with th e encum bering a nterior segments. Cnder th e microscope one can distinctly see the seg ment literally tearing itself slowly fro m the penultimate, a nd no tice the glutinous s tra nds be tween the m g rad uall y stretch as toffee stretches in pulling, until they finally pa rt as under and the a nte rior segments , united t o the posteri or onl y a t one edge , ha ng straig ht d own the side of the l att er. It may be remarked here that in a ll cases the posterior segm ent at the ti m e of separation was abo ut one-quarter longer than all the
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remaining segments. This was forcibl y brought to one's notice at the above stage of the proceedings, namely, when the anterior segments were hanging down the side of the posterior. The succeeding stage appears to be the most difficult (to a worm free in the intestine). The posterior segment again ceases its contractions for a few seconds. Then suddenly it appears to get into a fury, pushing upwards, sideways and forwards with tremendous energy, until it is finally freed from the other segments which remain passive in the mucus, while the posterior segment " pours " itse lf away at an amazing speed. Six separate worms were watched go through the above process, and in each case the method of procedure was identical. The time taken in each case was three-quarters of an hour from the time when the anterior segments, or rather the penultimate segment, became immobile. In th e intestines of the live fowl the head of the ce tode, in many cases (but not in all) would probably be fixed in the mucous membrane, thus rendering the procedure easier and probably more rapid. It must be remembered, however, that numerous complete, live cestodes were found free in the lumen of the bowel and it is to these that the foregoing description refers. Although the segments left behind were watched for some hours after th e secession of the posterior segments, no movement was observed in any of the six cases.
Egg of D. Proglottina. The egg of D. proglottina measures between 35,. and 40!'-, and is. globular in shape. It is surrounded by a thi n transparent cuticle and contains an oncosphere with six hooks, th e latter apparently always on th e top as th ey are always v isible. Under the one-third objective th ey look like minute cracks or folds in th e cuti cle of the embryo. U nder the high power one-sixth obj ective, th ey are seen to consist of an arm a t the end of which is the act ual " hook," like a crescent applied to the tip of the arm , the whole measuring between 10,. and 11,.. In some case the oncosphere does not appear entirely to fill the egg. In such cases careful focussing and illumination adj ustment will show two or three apparent lines radi a ting from the oncosphere t o the inner wall of the external shell of the egg. Closer examination will show that these lines are actually deep folds in an intra-ovular sac. In the cases where no such arrangement is observed, and where the oncosphere apparently fills th e entire egg, the " sac " is actually surrounding the oncosphere and is attach ed to it at the posterior end , the folds in the sac being oblitera ted.
OBSERVATIONS OK DOMESTIC FOWL
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A pos terior segmen t was t aken from so me freces immediately after e vacu a ti on, placed in a drop of water, under a cover-slip and examined under the microscope. It was q uite full of eggs a nd showed pronoun ced contractile powers. In less then five minutes the contractions ceased and the segment ruptured a t two points on either side of the anterior end . As it was suspected th a t the early rupture of the segment was due to pressure of the cover-slip another segment was placed in a drop of water in a h ollow ground slide a nd the cover-slip again applied, but th is tim e there was of course no pressure exerted on the segment. The contractions and expansions of this second segment continued for two hours with slight intervals of re t ; the movements graduall y become slower, a nd the intervals of rest longe r until at the end of this period the segment ruptured in the same places as in the first case. During th e movement of the segment the eggs within it could be seen tumbling over each other. When the contraction ceased, previous to rupture of the segment, careful examina tion showed hooks of the oncosph eres in m otion a nd a considera bl e number of oncospheres sh owed contrac tile movements within the eggs. From the ru ptures in th e segment eggs were extruded with a ce rtain a mount of force as if expelled by pressure from behind. A littl e later another rupture t ook pl ace in the main mass, from which num rous ova also were extruded.
The Embryo of D. Proglottina. In a ll li tera ture on cestodes to wh ich th e writer has had access, it is sta ted that . before th e oncosph ere can be libera ted from the egg, the shell an d embryonic envelope must be digested away by the gastric juices o f th e intermediate host. Leucka rt (" The P a rasite of ~I a n , " p. 33:-\) st a tes that" a sponta neous iiberation of t he embryo docs not occu r in th e Treni re." In a bout fiO per cent . of th e eggs of D. proglottina exa mined bv t he writer thi s was not fo und to be th e case. On the contra ry, ..,_;it hin five minutes aft er extrusion slight move ment of a n on cosph ere within th e egg was no ticed. As mentioned a bove some oncosph eres were showing moYement wh ilst still within th e segmen t. A watch was kept on one egg in which th e oncosphere was moving a t the time of extrusion. Th e oncosphere fi rst co ntracted slig htly, th e movement ex ac tly resembling a sligh t shrug of t he hould ers. It th en bega n to co ntract the \\"h ole " body " and t o elongate it much in the ma nn er of th e posterior segment. Slowly th e contractions and expansions becam e m ore pronou nced , and as the anterior end was thrust forwa rd the h ooks came into pl ay, catching in the envelope of th e egg and at
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tim es apparentl y penetrating it. The movement of the oncosphere grad u all y becam e more violent until , with a noticeable jerk the " egg shell " ruptured and the anterior portion of the oncosphere with its hooks shot out of the egg. Th e posterior portion was then withdrawn , bu t m ore slowly, and again careful focussing and illumination showed th at this slowness was due to the fact that the sac before m entioned was adh ering to the posterior part of the oncosph ere. Th e whole procedure took from half to three-quarters of an hour. On ce the oncosphere wa free of the egg it "swctm " v igorously and quickly away, the b ody contracting and expanding energetically and the two pairs of hooks at the sides being th rown forwards and outwa rds at each extension, exactly like a person using th e breast stroke in swimming, the central pair of h ooks h aving a n up a nd down m otion like a navvy using a pick. As a lready menti oned, the hooks are at th e end of a stiff arm which appea rs to be attached to or inserted in th e protoplasm of the anterior portion of the oncosph ere. Each arm with its hook can be moved sepa ra tely, but not as a n a nimal moves its limbs. On the contra ry , it seems as though the a rms were merely loosely attach ed a nd were thrown almost aimlessly at each vigorous ex tension of the oncosphere. Their m ovement is reminiscent of the ba ton as wi elded b y Punch or ra th er of Punch a nd the baton combined. As they are thrown out sideways a nd forwards, th ey cat ch in surrounding obj ec ts and ma terial , and a lso in neighbouring eggs and the reby assist in th e progress of the oncosphere. The body of the oncosph ere shows practically no structure, but appears to con ta in refrac til e granul es. There are two ma rkings resembling ridges or groove in the middle of th e posterior half on the dorsal surface. The free on cosph ere proceeds straight forward s. One came full against the posterior segment , which still conta ined large numbers of eggs and by thrashing about with its hooks within a very short time t ore an opening in the segment through which more eggs escap ed. Another in its travels came up against an egg containing a m oving oncosphere , but instead of turning aside it contracted a nd ex tended more vigorously than ever, the hooks catching in the envelope of the obstructing ovum, apparently by m ere chance it was pulled to one side a nd the oncosphere proceeded on its way. It is rather remarka ble in view of the previous observation that in spite of the vigorous play of the h ooks of the free oncosphere they did not tear th e " shell " of the ovum which they were attempting to pull out of the way . After leaving the egg the oncosphere is oval in form , although it is never still enough to say exactly what definite shape it is during
OBSE RVATI O ~ S
0~
DOMESTI C FO\iVL
31
life. The energy it di plays is extraord inary. One which bad beco me fixed in some debri s con trac ted and expanded with ou t the sligh tes t in te rmi ssio n for three hours, at the end of which time, wh en its obseiTation had perforce to be abandoned , it was still as ,-igorous as C \ "e L
Th e raising of th e tem perat ure of th e air surrounding th e microsco pe b\· means of o ne or two lighted Bunsen burne rs, apprec iably increased the rapid ity of " hatching," a nd th e activity of the oncospberes both intraov ula r and free, but in spite of this abo ut 40 per cent. of onco s ph eres within their respec tive eggs showed no movement at all. ~ ext day, however, no move ment whateve r could be obse n · d in eith er the free on cos ph eres or in those within th e egg. Th e above observ a tion s give rise to severa l interesting specula tions. \\"hy do 60 per cent. of oncosph ere hatch out a nd ap pa rently die in 24 hours, while 4.0 per ce nt . remain unh a t ched ? Is it a prov ision o f n at ure to prevent 0\·er-reprod ucti on of the s pecies? In other words , a re th e 40 per cent. destin ed to carry on th e race a nd a re the 60 per cent. merely the surplus? If so, wh a t facto rs influence t he viabi lity o f the oncos pheres? Th e last questi on may be p arti ally answered b y m entioning wa rmth a nd moisture wh ich undoubted ly increase th e d e,·elopme nt of movement in the oncosphere. On t he o ther ha nd, the same d egree of warmth and moisture was experienced by all the eggs in spite of whi ch some did not react a t all. Grassi and Hovelli stat that th e slugs will ea t segments of D . p roglottina in preference even to cabbage leaves. To test th is a -serti o n several slu gs ('- . agreshs) were placed in a petri d ish cont aining a defi nite number of segments, a nd small pieces of cabbage leav es. In spite of the fact that th e leaves were occasiona lly removed a nd th e slugs gi,·en n o o th er food , the latte r could not be indu ced to eat th e segments. Th e experiment was continued for 1-1 da,·s, th e segmrnts b eing carefull y counted a nd rep laced by fresh ones as th ey disintegrat ed. It m ay be that t he foregoin g a uth ors were deceived by th e sp ontan eous disintegrati on of t he segments, and im agined tha t such segments h ad been de\'oured b~ - the slugs . .-\ propos of th e h
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In one such outbreak, sections of the intestinal wall when examined microscopically, showed the cestodes to be present in very large numbers in the depths of the mucous membrane between the glands. Although complete worms, i. e., possessing posterior segments, they were o small th at no part of them projected into the lumen of the bowel and conseq uently they escaped observation by the hand lens. Amoebotaenia Sphenoides.
This minute tapeworm wa first recorded in this country by Meggitt (" On the Anatomy of a Fowl tapeworm Amoebotaenia · sphenoides v. Linstow, " Parasitology, Vol. VII, No.3, November 9th, 1914, p. 262). Th e writer ha been unable to find any references to its occurrence in this country sin ce that date. In six fowls from various parts of Glamorgansh ire he has found this parasite. In five of these instances it was associated with Dava·inea proglottina, but was the only type of cestode present in the other case, from which 12 complete specim ens ""ere obtained.
A CASE OF INTERSEXUALITY ASSOCIATED WITH DICHOTOMY OF THE CAUDAL REGION IN THE RABBIT. By ]. N. PICKARD, Animal Breeding R esearch Department , University of Ed·inbtt'rah.
A TYPI CAL Blue Beveren rabbit, well-grown for its age (16 weeks) was received on December 14th, 1926, from Mr. M. G. J ennings, of London. It was one of a litter of five, of which three were apparently perfectly normal , one which persi tently held its head on on e side, and the rabbit herein described, which was grossly abnormal and exhibited permanent torticollis. Both parents were normal and not closely related. On examina tion it wa noted t·h at it had two tails, two ani, and two penes. A penis had its origin at either side of a rna s of firm tissue covered with hair and si tuated immediately below th e t rue t ail. Th ere was, however, no bone present in this second tail. An a nus was also found behind each p enis. Urine was evacuated through either penis. The testes were never descended during life, and the
0~
D OME T IC FOWL
19
OBSERVATIONS ON DAVAINEA PROGLOTTINA IN THE DOMESTIC FOWL- WITH A NOTE ON AMOEBOTAENIA SPHENOIDES v. LINSTOW. By
ORMA
BISSET, M.R.C.V.S.,
.<,- ;ziUr T'ctcri11nry Ad1 •isory Officer, Uui< ·ersitv College of. 'o uth W ales,
Cardiff.
n.
ALTHO CC II proglott-ina has rece ived perhaps as much attention an tl im·cs tiga tion- parti cul arly from Continental wo rkers- as any , ,rher wor m ; and indeed is refe rred to bv tile;; as " one of th e few w•,rn h ,,·h ich is compara ti vely well known from a scientific poin t of vit·w ,·· , ·et , with th e excep tion of the work of :Yieggitt, little, if any, literature can be found on th e occurrence and effects of this minute Ch t odc of birds in thi s country . It is. therefore, pro posed to d escri be in ·de ta il an outbreak of d i ~case in a fl oc k of fowl s. in wh ic h two different t ypes of parasites, Yiz., cestode a nd protozoan, co mbined their attacks, the ces tode being LJ. proglottina , a nd th e protozoan Fimeria a1•i11 111. . ince that outhreak whi ch was th e lirs t occasion on which D. proglottina was dis' "'·ered b~ · the writer , and which occurred in 1924. the parasites have bt:en encoun tered in an ever-increasing number of cases from different diq rict s in C lamorgan a nd Monmou thshire. Tt ma\· well be that , since th e outbreak in q uestion , s pecial attention has been directed t " th t; presence or a bsence o f D . proglottiua . which. owing to it s minute ;;izc . is ca,-ih' o\·e rl ooked , especiall y wh en unexpec ted. The writer ma \ · as well confess at once th at llC' \\'as taken b\· s urprise in the fn·;; r instan ce, as will ap pear later. Th e fact rema in ·, howe,·e r . t ha t in the ca::e of e \·ery fow l on \\ hich a post-m ortem examinat ion has been conducted , a thorough {> \a mination fo r pa rasites, both mac rosco!)iC and microscopic, external ;,nd intern al. h as im·a ri ab ly been made a~ a rou tine procedure, and u nt il th e outbreak about to be desc ribed , D. proglottina had not been (,] •:::en ·ecl. :-;in ce that time . as mentioned a bove. the parasites or th eir ]"•~ terior seg ment s ha,·e been fou nd . in excreta from li ve fow ls, a nd '•n posl-morlelll ex a mi na tion in a rapidl y increasing number o f instances, in .til of \\·hi ch the paras ites h a ,·e been quite ob,·ious to the naked eye, ' " m uch so th at it is d ifficu lt to imagine tha the~· co uld ever ha,·e 1Jn· n ()\·erlooked .
.\ consi derable number of fow ls wh ich had ceased laying, lost ,-,.. nd iti on , a nd become ge nera l!\· unthrifty, and in the excre ta of which nu m erotb posterior segmen ts have beeri fo und, h a ,·e been treated ln the int rodu cti on in to the crop of a teaspoonful of turpentine, the
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fowls h aving previously been fasted a nd dosed with Epsom salts. These fowls have, in every case, after a second dose of salts given four hours after the turpentine, expelled the parasites in numbers varying from 100 to 300 and in a short time h ave recommenced laying a nd put on fl esh, the average time taken for recovery being betweeJ1 two and three weeks. It would appear, therefore , that the cestodes exercise rather more of a detrimental effect on their hosts than has hitherto been supposed. The outbreak in question occurred in a fl ock of White W yandottes, numbering 30 in all. The fowl s had all been h atched on the premises, and none h ad been introduced from ex ternal sources. They were of various ages, b ut those which showed signs of illness were all aged between two and three months. The symptoms commenced to appear when the birds were on e month old previous to which time the whole flock was apparently in perfect h ealth. Before the writer was consulted two " diagnoses " of the condition had been obtained by the owner from different sources. The first blamed the feeding and ascribed t he disease, which, however, wa not defined , to th e eating of decayed wind-fallen apples. The second reported the cause of th e trouble to be coccidiosis. The owner then referred to the writer who visited th e premises a nd examined the flock and its surroundings. Twenty-three birds were left , but no isola tion had been practised . Seven older fowls appeared healthy, but 16 birds of eight to ten weeks old were showi ng symptoms of disease . They all had the run of a small orcha rd, about one-sixth of an acre in extent. The houses appeared clean and well looked aft er. Th e owner described the symptoms of those fowls which had died as dullness, p rog ressive and rather rapid emaciation, paleness of the comb a nd skin of the h ead and a tendenC\' to seek seclusion and to stand for lon g p eriods in a " hunched-up " posi tion. Four birds ou t of seven h ad " died m convulsions." An examination of the 1(i affected birds conlirmed the owner 's description . In the h ouses they stood in the " hunched-up " position in attitudes varying from medi tative to misera ble, n ow and again closing the eyes and allowi ng th emselves to be pushed aside by the a ppa rently unaffected birds. The " ruffled feathers" so evident in tex t-book description s of p oultry diseases were not noticeable. The tail was drooped and the head sunk between t he sh oulders. The comb, wattles and skin of the head were mark edly amemic- in most cases quite blanched with no sign of pink colour whatever . Th e
OBSERVATION S ON DOMESTIC FOWL
21
d roppings were watery at one evacua tion , apparently normal a t ano ther, a nd slimy and of a reddish colour at yet anoth er. There was, however, no evidence of true white diarrhcea such as is associated with coccidiosis in young chicks. The birds were very emaciated and extraordinarily light wh en handled . On bei ng put into the run they a ttempted to resume their somn olent attitude, but on being forced to move they showed distinct weakness of t he legs. Once forcibly livened up and on food b eing offered . th ey ate Yor aciously for a short time and then relapsed into their fo rm er comatose state. The eyes when opened w ere quite bright , but somewhat" sunken. The owner m entioned the fact of the appetite being maintained a nd , indeed somewhat increased, but stated that fo r abo ut 24 hours before death all appetite was lost. Bearing in mind both previous reports on the cause of the disease, which had , naturally, somewh at confused the owner, the writer by a little cross-examination elicited the following facts: (1) Thi s was the first outbreak of disease of any kind on th ose premises. (2) No birds h ad been introduced from external so urces. (3) The fowl s had always been fed in the same way a nd h ad always at th e proper season had access to the wind-fallen apples, th e orcha rd being their run .
(4) Dia rrhcea had been noti ced in two in stances only out of the 23 affected. The se ven apparently health y birds were immediately isolated and permission wa s g ran ted for the slaughter and post-mortem e xamination of what appeared to be th e worst case, which was brought to the laboratory for th e purpose. Th e fowl was ex trem ely emaciated a nd showed a ll the above-mention ed symptoms, including bl anching of the comb a nd skin of th e head. Post ~ Mortem.
Th e internal organs at fi rst glance appeared normal except t hat the gall bladder was en larged, and that a ll fat seemed to have dis<~ppeared. Th e li ver was p erfectly clean and normal in colou r an d the c
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THE VETERI NARY JOURNAL
greenish coloured fc:eces. The duodenal wall were considerably thick ened and th e mucous membrane was dotted wi th pe techial 11c:emorrh ages which also , though to a less degree, extended throughout the small intes tine. None were present in the cceca. Examin ation ·of wet films of the intes tinal contents revealed coccidial oocysts. These were fairly numerou s. but not nearly to such an extent as one may ·ee in a t ypical ca e of coccidiosis in a chick a fort nigh t oldwhere th e li \'er and cceca a re typically affected . While the wri ter was examining th e film from the duode nal contents th ere was a swirl at th e edge of the field , a nd into it ca me .a large body p ossessing amazing contractile p owers and p rog ressing by contracting itself in to a ball , followed by Yigorous extension. T he best description of its movement one ca n think of is to say that it poured itself along. T he body appeared to ha ve neither head nor tail, but it proceed ed always so to speak " head ·· fi rst, i. e., it had to t urn round to move in a reverse direction . It was full of minute ovoid bodies. Following it came two others, one of which . however, had a ttached to the " anterior " end two smaller bodies. On fu rther ex amin a ti on of the tilm numerous oth ers were found. The duoden al muco us membrane was th en exami ned by means of a han d lens when very numerous elongated oval bodies could be seen apparently a ttached to the mucous m embra ne and s~a nding up on end in the muc us which was adherent thereto . .\ scraping from the mucous m embra ne was examined micro. copically. About a dozen minute tapeworms were found in t he scraping, some con isting of fi ve segments and othe rs of four. T he large " b odies" descri bed above were the posterior segmen ts which had become detached . These tapeworms, which were fo und to be Davainea proglottinn, will be described in detail belo\1'. , II the parasites, or to be more exact, th eir posterior egmen ts, were very active . Th e hao morrhages in the intestinal wall appeared through the h and lens as if they h ad been made with a camel h ai r brush, or as if the ces todes h ad scratched the mucous membran e wi th th eir hooks. A before menti oned, th ey were most numerous in the d uodenum , .but were eviden t th e whole length of the small intes tin e. Th e paras ite also were less numero us in the la rge intestin e and in th e cceca none were fo und. Th e cceca a nd their contents, it should be emph asised, were macroscopical!\· nonn al in every way, i.e. , the wall;; we re not thickened , nor were the contents cheesy or inspissated though oocys ts were fo und therein. Co mpl ete five-segmen ted or four- egmented worms we re found .only in t h e d uoden um and mostly in the branch connected \\'i th the
OB ERVATION S
0~
DOMESTIC FOWL
23·
gizzard. Further down th e intestin e three, two and one segment s were fou nd , but no heads. Wh ere a ny da rk coloured intestin al contents were present the la rge posterior segments cou ld be di stinguished with th e na ked eye against th e dark background a nd t heir contractions co uld also be observed with out th e aid of a lens. T hev were much more diffi cult to see again st th e actual mucous membrane ?\ ext day word was received that two other bircl s had d ied , one " in convulsions." t hi s in spite of the fact th at t he fow l examined tlw day b efore h ad been carefull y chosen as showing most obvious symptoms of illn ess. T hese two fowls were brought to t he labo ra tory and ex amin ed. Th ey were also emacia ted , amem ic, and ex tremely light. The crops were 1uite empty . A in the f1rst case, a t fi rst glance the in tern al organs appeared normal ex cept for enl argement of the gall bladder a nd absence of fat ; b ut in the case of the one which was reporterl to h ave died in convulsion s th e intestin e, besides showin g t he red and purpl e spots on the peritoneal surface was of a rosy pink colou r t h ro ughout . On opening it the m ucous m embrane of th e duodenum presented an appalling condition due to the hcemorrh ages. One p a tch in size about } in . by t in . near the gizzard was almost black , while the appearance of the res t of the mucous membrane of the sma ll intestine could b est be descri bed as clark purple reel with minute white points, t hose b eing the only parts left of the norm al mucous membra ne. The co ntents con sisted of tenacious brown ish or p inkish mucus in which we re clots of blood and lively posterior segments of D. proglottina. Through the mucus t he hcemorrh ages co uld be seen. The mucoid in testinal contents were lightly scraped away wh en it was noticed that the hcemorrh agic mucous membrane presented a rather cloud \· a ppearance as though a fi lm were over it. Ex amin ation with a hand lens showed it to b e ·o th ickly studded with the ces todes that the po in t of a p in could barely be placed between th em. Th ey reminded o ne forcibly of t he papilla: of th e mucous membrane of the rumen of t he ox. As b efore, t he worms appea red to be s tand ing on their heads, t!I posterior segments bein g a ll that could be seen , although numerou s pos t ' rior segm ents and com plet e wom1s were ly ing longitudinally and t ransversely on to p of the other . So num erou were the parasites that it was practically im possible to count them. This "mass form ation "ex tended for a lmost h alf th e length oi the intes tinal t ract and it is noteworthy th at the hcemorrh ages were less num erous in the latter half, although in this case th ey were found t hroughout the whol e length including the cceca. Segments of worms were a lso found throughout th e comple te intestin al tract except the cceca, but
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THE VETERINARY JOURNAL
no heads were found posterior to the end of the extraordin ary m assed formation. Again there were no obvious macroscopic signs of coccidiosis so far as regards the appearance of the li ver and cceca. With the exception of the few isolated hcemorrhages in the latter, they appeared quite normal in every other respect . Coccidia were found, however, .in the intestinal contents, but as before they did not appear to b e p resent in excessive numbers. The findings on opening the intestines of the other fowl corresponded with those noted in the first specimen ; hcemorrh ages a nd worms being plentiful and oocysts also being found . :\ visit was immediately paid to the affected premises. Exhaustive search was made for slugs (Limax) without result. No marshy land or streams were in the immediate vicinity. It should be noted that no trace of slugs was found in any of the birds examined. Three of the remaining birds which seemerl most seriously affected were brought to the laboratory. Two were killed a nd examin ed with the same result- abundance of hcemorrhages and cestodes, Coccidia present , bi.tt liver and cceca and ccecal contents normal in appearance. The third fowl was kept under observation in a special cage so constructed th a t the droppings could be easily collected for ex~ min a ti on . (It m ay be mentioned here tha t treatment was sugges ted and drugs were actually procured , but it was found a few days later that the owner had destroyed the remaining birds and burnt the carcasses.) • The droppings of the last-mentioned fowl varied in consistency. Some evacua tions appeared quite normal in consistency , but were partly dark green and partly brown or reddish brown. Others were softer, but all were formed to a certain extent, i.e., there was no true diarrhcea. Numerous vigorously moving posterior segments from .;;, in. up to almost ~ in. in length could be easily seen on th e surface of the droppings. Some were globular like pin heads, a nd about the same size. The ma jority were not "crawling about," but were stretching out their a nterior portions from the surface of the exc reta .and waving to an d fro very much like a cobra preparing to strike. vVithin a few minutes, however, they left the excreta a nd proceeded to "crawl" away from it. 'Within an hour, on a large tray on a bench top, without the assistance of any additional m oisture several of these segments had reached a dis tance of two feet from th e excreta. This fact was noted from the examination of subsequent droppings, but from the surface of the first evacuation after the fowl had b een placed in the cage 65 segments were easily picked off. The droppings were then teased apart , a nd it was found that the dark green portion was normal in consistency throughout, while the brownish-red portion consisted of blood-stained extremely tenacious mucus with here and
OBSERVA TIO~ S 0:\ DOMESTI C FOWL
25
1hcre blood clots and lum p~ of a clear _ye llowish jelly. Pos terior :'l!g men ts were fo un d in bo th t he a pparentlv normal a nd the mucoid l<•.: cret J. which were well teased apa rt a nd was hed with wa ter. In all l 14 segments were fo und in the one evacuatio n . .-\n hour later a nother evac ua tion was passed a nd exa mined in a o'im il a r manner, but onl y 27 segmen ts were picked out. The droppings th is tim e were entirely reddish-bro wn mucoid materi al, but were m ore :fluid a nd not so well formed as previously. F ro m a t hird evac ua tion a bout an hour later bu t fo ur segm ents were removed. As this fowl ,,-as ke pt as a so urce of sup ply of t he para~ i tes no treatment was .a ttem pted , and it is rem a rkable th at a lth ough it was one of the m os t ma rkedll· affected wh en removed from t he tloc k a nd should by a ll .a ppearan ces have di ed within a few clays , yet not only did it sur vive fn r a lm ost six wee ks, but it also los t the somn olent appearance to a certain ex tent and a slight trace of colour began to return to th e comb . At the end of th a t t ime it was kill ed a nd a!t ho ugh coccidia, cestocles a nd hcemorrh ages were found as b efo re, all three were present in a Jess deg ree th an in the other fi ve fowl s examined , as th ough th e nat ura l resista nce of the body had been success ful to a certa in point in dealing with bo th ty pes of pa rasites alrcach · present when once the host was removed from the risk of fresh infec ti on. Th ere is probab ly little d oubt th a t th e ac tu a l cause of death was coccidiosis, alth ough the absence of lesions on the li ver and a lso of the enla rged cceca with th eir cheesy contents is ra th er rema rka ble. It is, of course, well kn own th a t a condition of h
As descriptions of D . proglottina have a !ready been publi shed , a nd as the observa tions of th e writer a gree with th em in prac t ica ll y all respects, it wi ll suffi ce he re to quote the description given by Stiles
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THE VETE RINARY JO URNAL
(Tap eworms of :Poultry , BU LL 12, U .S. Dept. of Agric. Bureau of Animal Industry, p . 47) :"Diagnosis: 0 · 5 mm. to 1 · 55 mm . long b y 0 ·18 mm. to 0.50 m m. broad. H ead club shaped to q uadrangular, 140,u. to 250,u. long by l35t-t to 200,u. broad, rather rounded in front and slightl y constricted in back to form neck (10 ,u. broad) ; apex a rmed with retractile hemispherical rostellum 55,u. in its a ntero-pos terior diameter and 601'- to 85,u. in its lateral diameter ; base of rostellum armed with about 80-95 h ooklets measuring 6 · 5,u. to 7 · 5,u. Suckers circular, small (251'- to 35,u.) armed with a single row of hooklets (6t-t), with rather large, bilohed base. Strobila composed of two to five segments , first segment only about 56!'- long, the following segments increasing in length a nd width. Genital pores irregularly alternate, situated at the anterior angle. The second segment possesses well-developed male organs and th e anlagen of female organs. In the third segment the testicles a re a trophied , the female organs (median posterior vitell arium , two ovaries, recept. sem. vagin a) well de veloped, but no uterus present. In th e fo urth segment all the genital glands are atrophied, and the segment is fill ed with numerous isolated eggs (not in egg capsules), ova 35p. to 401-'; hooks of oncosphere 101'to 111-', The segments have a great tendency to separate more or less completely ; the last segment, after separating, remains in the intestine and grows to 2 mm. long by 1 · 25 mm. broad (la rger than the entire worm)." To the above description the following obse rvations on th e worms found in the foregoing cases may be added :LENGTH.- Several complete worm s were found to b e 2 mm. in length. NUMBER Of SEGMENTS.-No two-segmen ted worms were foun d. The average number was five , but fours were also common. This applies to the obviously complete worm . Numerous three-segmented worms were observed from whi ch the posterior segment had apparently just separated , but as t hese might h ave been accidentally broken they were not considered. Th e total length of the cestode depends , of course, on the number a nd size of the segments, particularly the size of the posterior segment. SucKERS.- The suckers are four in number and agree in dimensions with Stiles 's figures, but the booklets urrounding them are i n triplicate a nd not in a single row, as they are found round the b ase of the rostellum. Th e hooklets a re shaped like a ha mmer. THE PosTERIOR SEGIIIENT.- This segment appears to b e the most important part of the whole parasite. Indeed , it is not exaggerating
OBSERVATIONS ON DOMESTI
FOWL
27
n ' n · much t o say th a t it a ppears to contain the " intelligence" as
wel l a the mo tive powe r. The penultimate seg ment shows feebll' contract ile powers, but in those a nterior to it no movement whatever could be observed. They a ppear to be pushed this way and that at the " will " of the posterior . egment , whic h shows a mazing energy , becoming altern a tely globul a r and then linear, as it pours itself along, pushing its unresist in g " passengers" in front of it , as it would do when free in t he lumen of the in tes tin e. The pos terior egment is co mpl cte lv fill ed with eggs contai nin g oncos ph eres. Separation of Posterior Segment.
Th e se pa rati on of the post eri or segment from the res t of th e strobila hy no mea ns a simpl e decidu ous process like a d ead lea f falling fro m a branch, and it is interes ting to wa tch under the micro cope the casting off of the posterio r segment or rather the casting off of the an terior segments by the posterior , for that appea rs to be a more accura te de. cription of th e process. IS
lt mus t be borne in mind that the descripti on appli es to a parasite examined Sltper vitrmn, i. e ., on a slide.
As be fore mentioned , th e penultima t e segment shows compa ra tively feeble co ntractile powers during progression. When the time h as come for the posteri or segmen t to se para te, the other segments incl uding th e p enultimate become 4u it e immobile. The p ost eri or seg ment then in creases its contractions, and , as it p ushes forward , lirs t with long s teady s trokes, a nd th en wi t h li ttle jerks, as if it were indeed senti e nt , the a n terior segments fa ll slowly to one side. The sticky tenacious mucus appa rentl y he lps to so me extent in the procedure by re taining the a nteri or segments , while the p os terior ,.;eg mcn t t ea rs itself away . .\ fter a littl e ti me the posterior seg ment ,.;eem;; to become tired , th e contractions become slower, a nd ti.nally cease for a few seconds. Then with redoubl ed force they recommencelong steady st rokes , a ltern ated with jerks, the anterior egmen ts falling more a nd mo re t o the side. 1t would almost appear at times as if t he po terior segment were shaki ng its " head" like a terrier with a rat , as if in annoyance with th e encum bering a nterior segments. Cnder th e microscope one can distinctly see the seg ment literally tearing itself slowly fro m the penultimate, a nd no tice the glutinous s tra nds be tween the m g rad uall y stretch as toffee stretches in pulling, until they finally pa rt as under and the a nte rior segments , united t o the posteri or onl y a t one edge , ha ng straig ht d own the side of the l att er. It may be remarked here that in a ll cases the posterior segm ent at the ti m e of separation was abo ut one-quarter longer than all the
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remaining segments. This was forcibl y brought to one's notice at the above stage of the proceedings, namely, when the anterior segments were hanging down the side of the posterior. The succeeding stage appears to be the most difficult (to a worm free in the intestine). The posterior segment again ceases its contractions for a few seconds. Then suddenly it appears to get into a fury, pushing upwards, sideways and forwards with tremendous energy, until it is finally freed from the other segments which remain passive in the mucus, while the posterior segment " pours " itse lf away at an amazing speed. Six separate worms were watched go through the above process, and in each case the method of procedure was identical. The time taken in each case was three-quarters of an hour from the time when the anterior segments, or rather the penultimate segment, became immobile. In th e intestines of the live fowl the head of the ce tode, in many cases (but not in all) would probably be fixed in the mucous membrane, thus rendering the procedure easier and probably more rapid. It must be remembered, however, that numerous complete, live cestodes were found free in the lumen of the bowel and it is to these that the foregoing description refers. Although the segments left behind were watched for some hours after th e secession of the posterior segments, no movement was observed in any of the six cases.
Egg of D. Proglottina. The egg of D. proglottina measures between 35,. and 40!'-, and is. globular in shape. It is surrounded by a thi n transparent cuticle and contains an oncosphere with six hooks, th e latter apparently always on th e top as th ey are always v isible. Under the one-third objective th ey look like minute cracks or folds in th e cuti cle of the embryo. U nder the high power one-sixth obj ective, th ey are seen to consist of an arm a t the end of which is the act ual " hook," like a crescent applied to the tip of the arm , the whole measuring between 10,. and 11,.. In some case the oncosphere does not appear entirely to fill the egg. In such cases careful focussing and illumination adj ustment will show two or three apparent lines radi a ting from the oncosphere t o the inner wall of the external shell of the egg. Closer examination will show that these lines are actually deep folds in an intra-ovular sac. In the cases where no such arrangement is observed, and where the oncosphere apparently fills th e entire egg, the " sac " is actually surrounding the oncosphere and is attach ed to it at the posterior end , the folds in the sac being oblitera ted.
OBSERVATIONS OK DOMESTIC FOWL
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A pos terior segmen t was t aken from so me freces immediately after e vacu a ti on, placed in a drop of water, under a cover-slip and examined under the microscope. It was q uite full of eggs a nd showed pronoun ced contractile powers. In less then five minutes the contractions ceased and the segment ruptured a t two points on either side of the anterior end . As it was suspected th a t the early rupture of the segment was due to pressure of the cover-slip another segment was placed in a drop of water in a h ollow ground slide a nd the cover-slip again applied, but th is tim e there was of course no pressure exerted on the segment. The contractions and expansions of this second segment continued for two hours with slight intervals of re t ; the movements graduall y become slower, a nd the intervals of rest longe r until at the end of this period the segment ruptured in the same places as in the first case. During th e movement of the segment the eggs within it could be seen tumbling over each other. When the contraction ceased, previous to rupture of the segment, careful examina tion showed hooks of the oncosph eres in m otion a nd a considera bl e number of oncospheres sh owed contrac tile movements within the eggs. From the ru ptures in th e segment eggs were extruded with a ce rtain a mount of force as if expelled by pressure from behind. A littl e later another rupture t ook pl ace in the main mass, from which num rous ova also were extruded.
The Embryo of D. Proglottina. In a ll li tera ture on cestodes to wh ich th e writer has had access, it is sta ted that . before th e oncosph ere can be libera ted from the egg, the shell an d embryonic envelope must be digested away by the gastric juices o f th e intermediate host. Leucka rt (" The P a rasite of ~I a n , " p. 33:-\) st a tes that" a sponta neous iiberation of t he embryo docs not occu r in th e Treni re." In a bout fiO per cent . of th e eggs of D. proglottina exa mined bv t he writer thi s was not fo und to be th e case. On the contra ry, ..,_;it hin five minutes aft er extrusion slight move ment of a n on cosph ere within th e egg was no ticed. As mentioned a bove some oncosph eres were showing moYement wh ilst still within th e segmen t. A watch was kept on one egg in which th e oncosphere was moving a t the time of extrusion. Th e oncosphere fi rst co ntracted slig htly, th e movement ex ac tly resembling a sligh t shrug of t he hould ers. It th en bega n to co ntract the \\"h ole " body " and t o elongate it much in the ma nn er of th e posterior segment. Slowly th e contractions and expansions becam e m ore pronou nced , and as the anterior end was thrust forwa rd the h ooks came into pl ay, catching in the envelope of th e egg and at
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tim es apparentl y penetrating it. The movement of the oncosphere grad u all y becam e more violent until , with a noticeable jerk the " egg shell " ruptured and the anterior portion of the oncosphere with its hooks shot out of the egg. Th e posterior portion was then withdrawn , bu t m ore slowly, and again careful focussing and illumination showed th at this slowness was due to the fact that the sac before m entioned was adh ering to the posterior part of the oncosph ere. Th e whole procedure took from half to three-quarters of an hour. On ce the oncosphere wa free of the egg it "swctm " v igorously and quickly away, the b ody contracting and expanding energetically and the two pairs of hooks at the sides being th rown forwards and outwa rds at each extension, exactly like a person using th e breast stroke in swimming, the central pair of h ooks h aving a n up a nd down m otion like a navvy using a pick. As a lready menti oned, the hooks are at th e end of a stiff arm which appea rs to be attached to or inserted in th e protoplasm of the anterior portion of the oncosph ere. Each arm with its hook can be moved sepa ra tely, but not as a n a nimal moves its limbs. On the contra ry , it seems as though the a rms were merely loosely attach ed a nd were thrown almost aimlessly at each vigorous ex tension of the oncosphere. Their m ovement is reminiscent of the ba ton as wi elded b y Punch or ra th er of Punch a nd the baton combined. As they are thrown out sideways a nd forwards, th ey cat ch in surrounding obj ec ts and ma terial , and a lso in neighbouring eggs and the reby assist in th e progress of the oncosphere. The body of the oncosph ere shows practically no structure, but appears to con ta in refrac til e granul es. There are two ma rkings resembling ridges or groove in the middle of th e posterior half on the dorsal surface. The free on cosph ere proceeds straight forward s. One came full against the posterior segment , which still conta ined large numbers of eggs and by thrashing about with its hooks within a very short time t ore an opening in the segment through which more eggs escap ed. Another in its travels came up against an egg containing a m oving oncosphere , but instead of turning aside it contracted a nd ex tended more vigorously than ever, the hooks catching in the envelope of the obstructing ovum, apparently by m ere chance it was pulled to one side a nd the oncosphere proceeded on its way. It is rather remarka ble in view of the previous observation that in spite of the vigorous play of the h ooks of the free oncosphere they did not tear th e " shell " of the ovum which they were attempting to pull out of the way . After leaving the egg the oncosphere is oval in form , although it is never still enough to say exactly what definite shape it is during
OBSE RVATI O ~ S
0~
DOMESTI C FO\iVL
31
life. The energy it di plays is extraord inary. One which bad beco me fixed in some debri s con trac ted and expanded with ou t the sligh tes t in te rmi ssio n for three hours, at the end of which time, wh en its obseiTation had perforce to be abandoned , it was still as ,-igorous as C \ "e L
Th e raising of th e tem perat ure of th e air surrounding th e microsco pe b\· means of o ne or two lighted Bunsen burne rs, apprec iably increased the rapid ity of " hatching," a nd th e activity of the oncospberes both intraov ula r and free, but in spite of this abo ut 40 per cent. of onco s ph eres within their respec tive eggs showed no movement at all. ~ ext day, however, no move ment whateve r could be obse n · d in eith er the free on cos ph eres or in those within th e egg. Th e above observ a tion s give rise to severa l interesting specula tions. \\"hy do 60 per cent. of oncosph ere hatch out a nd ap pa rently die in 24 hours, while 4.0 per ce nt . remain unh a t ched ? Is it a prov ision o f n at ure to prevent 0\·er-reprod ucti on of the s pecies? In other words , a re th e 40 per cent. destin ed to carry on th e race a nd a re the 60 per cent. merely the surplus? If so, wh a t facto rs influence t he viabi lity o f the oncos pheres? Th e last questi on may be p arti ally answered b y m entioning wa rmth a nd moisture wh ich undoubted ly increase th e d e,·elopme nt of movement in the oncosphere. On t he o ther ha nd, the same d egree of warmth and moisture was experienced by all the eggs in spite of whi ch some did not react a t all. Grassi and Hovelli stat that th e slugs will ea t segments of D . p roglottina in preference even to cabbage leaves. To test th is a -serti o n several slu gs ('- . agreshs) were placed in a petri d ish cont aining a defi nite number of segments, a nd small pieces of cabbage leav es. In spite of the fact that th e leaves were occasiona lly removed a nd th e slugs gi,·en n o o th er food , the latte r could not be indu ced to eat th e segments. Th e experiment was continued for 1-1 da,·s, th e segmrnts b eing carefull y counted a nd rep laced by fresh ones as th ey disintegrat ed. It m ay be that t he foregoin g a uth ors were deceived by th e sp ontan eous disintegrati on of t he segments, and im agined tha t such segments h ad been de\'oured b~ - the slugs . .-\ propos of th e h
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In one such outbreak, sections of the intestinal wall when examined microscopically, showed the cestodes to be present in very large numbers in the depths of the mucous membrane between the glands. Although complete worms, i. e., possessing posterior segments, they were o small th at no part of them projected into the lumen of the bowel and conseq uently they escaped observation by the hand lens. Amoebotaenia Sphenoides.
This minute tapeworm wa first recorded in this country by Meggitt (" On the Anatomy of a Fowl tapeworm Amoebotaenia · sphenoides v. Linstow, " Parasitology, Vol. VII, No.3, November 9th, 1914, p. 262). Th e writer ha been unable to find any references to its occurrence in this country sin ce that date. In six fowls from various parts of Glamorgansh ire he has found this parasite. In five of these instances it was associated with Dava·inea proglottina, but was the only type of cestode present in the other case, from which 12 complete specim ens ""ere obtained.
A CASE OF INTERSEXUALITY ASSOCIATED WITH DICHOTOMY OF THE CAUDAL REGION IN THE RABBIT. By ]. N. PICKARD, Animal Breeding R esearch Department , University of Ed·inbtt'rah.
A TYPI CAL Blue Beveren rabbit, well-grown for its age (16 weeks) was received on December 14th, 1926, from Mr. M. G. J ennings, of London. It was one of a litter of five, of which three were apparently perfectly normal , one which persi tently held its head on on e side, and the rabbit herein described, which was grossly abnormal and exhibited permanent torticollis. Both parents were normal and not closely related. On examina tion it wa noted t·h at it had two tails, two ani, and two penes. A penis had its origin at either side of a rna s of firm tissue covered with hair and si tuated immediately below th e t rue t ail. Th ere was, however, no bone present in this second tail. An a nus was also found behind each p enis. Urine was evacuated through either penis. The testes were never descended during life, and the