THE CIRCULATION IN THE CRUSTACEA.

135 the epidermis, being in ease. It was in order to attain this end, certain spots, only a white line analogous to that Messrs. Milne Edwards and Audouin, the epidermic layer of the papillæ; in took up their abode at Granville, a small others thicker, harder, and as if it were town situated on the borders of the channel, formed of a series of scales placed on each where they were sure of meeting with the other, being certainly the superficial white necessary means for prosecuting their layer of M. Gaultier, the horny layer of AI. studies, and where they collected the mateDutrochet. Thus pathological anatomy has, rials of the great work which they have says M. Arnold, confirmed what the philo- laid before the Academy. sophy of anatomy had already led us to pre- In the brief exposé we are about to make sume, that the skin of a white man is form- of the researches of our authors, we shall ed of the same substance as that of thenot the order which they have adopt exactly and animals; this substance, according followed. Their first paper contains the negro to the species, either acquiring the greatest chronological history of the knowledge acpoint of development, or remaining rudi- quired, and of the opinions entertained rementary. specting the circulation in animals belonging to this class ; they next relate, with the most THE CIRCULATION IN THE CRUS-minute detail, the experiments which they performed on living crustacea, in order to TACEA. ascertain the mode in which circulation goes WE have received, from our Paris Corres-on in those animals. pondent, the following report, made to the The second memoir comprises the anapart of Messrs. Milne Edwards, Royal Academy of Sciences by Cuvier andtomical and Audouin’s researches, and the deDumeril, the members of a commission ap- scription of each of the organs belonging to pointed to investigate the merits of an in-the circulatory system. It is illustrated by coloured plates, in which the mode teresting paper read to the Academy, en-twenty of distribution of the different blood-vessels titled " Anatomical and Physiological Re-is represented in divers crustacea, brachyars, searches on the Circulation in the Crusta-macrouri, and stomapodi. This comparacea," by Drs. H. Milne Edwards, and V. tive description, which is presented with great minuteness, shows that in most aniAudouin. The report is highly compli-mals of this class, circulation is carried on mentary to the talents of these gentlemen,, in the following manner :--. The blood or liquid, which is set in moand has not yet been printed in any other tion by the contractions of the heart, peneJournal :trates into the cavity of that organ, by means In all the most recent works on the organi-of two large branchio-cardiac vessels, the sation of the crustacea, the accounts given oif orifices of which are provided with valves the circulation in those animals are most erro-so disposed as to hinder any retrograde neous ; for the authors, instead of examining,. motion of the circulating fluid; six large the question in an experimental manner, hadvessels arise from the heart,and constitute contented themselves with combining thethe arterial system ; three of these take course forwards, and carry the blood to ill-established results obtained by Willis and the antennæ, and the neighbouring the the the auwith facts ascertained eyes, others, by thor of the lectures on comparative anatomy.parts; two other arteries descend almost This subject called, therefore, for new andperpendicularly, and distribute their branches accurate investigations, not only as to theto the different lobes of the liver ; the last, mode in which the circulation is actually car-. which is the most considerable, and may ried on, but also concerning the anatomicalbe considered as an aorta, supplies the structure, and the distribution of the vascu-. lower part of the thorax, the abdomen, the lar system. But, in order to throw newposterior extremity of the animal, and all light on this part of general physiology andthe appendices of the body. In all these animals, the veins appear to comparative anatomy, the study of any single species of crustacea would not have beenIbe in direct communication with the termisufficient, nor could it be prosecuted on ani-nations of the arteries, but their coats are mals whose organs are hardened, or more’ so extremely thin and delicate, that they or less modified by the means usually re-- seem to be formed only by a species of sorted to in order to preserve them in ourr cellular membrane fixed to the substance of museums ; and it was consequently neces-the organs which they pass through; a dissary that these researches should be carriedi position somewhat similar is met with in on near the sea coast, where the crustacea,, the veins of the dura mater in mammalia, whose form and structure present the mostt and one of us had also noticed it in certain striking difference, can be procured witht species of fish belonging to the class cy-

lying quite beneath

] their

136 clostoma. It renders the dissection oiintroduction of air into the branchial vessels these organs extremely difficult ; and it is of a living animal, for its progress in the only by insufflation, or by injectingthe vascular svstem rendered visible the course veins with coloured fluids, that Messrs, followed by the blood. When the air was Edwards and Audouin, were able to render sent into the efferent vessel, it did not pass out of the branchia ; but when introduced them visible. All the ramifications of the venous system into the efferent vein of those organs, it terminate in one or two large sinuses or penetrated into the cavity of the heart, and reservoirs, situated on the sides of the was propelled into all the other vessels thorax, and surrounded by thin crustaceous arising from the heart, and which constitute or bony lamina, which constitute a certain the arterial system ; and, lastly, the fourth number of cells communicating with each experiment proves, that coloured fluids inother; the vessels situated on the outer jected into the venous sinuses, penetrate surface of the branchial pyramids, take from thence into the branchia by means of their origin from these sinuses, and their the efferent veins. branches communicate with the ramificaSuch are the facts positively established tions of other vessels, which take their by these interesting researches, which are course along the inner side of the respira- calculated to throw great light on this part tory organs. These latter veins are the of comparative anatomy, and which it is to efferent ducts, which carry the blood back be hoped the scientific world may soon be to the heart, at the side of which they able to profit by. We therefore propose, open, after having united to form a single that the Academy should order this work to trunk, the orifice of which, as we have al- be published in its collection of the " Meready mentioned, is provided with valves moires du Savans Etrangers." intended to hinder the blood from returning BARON CUVIER. CUYlER. (Signed) towards the branchia during the contraction DUMERIL. of the heart. The conclusions of this report are adopted Such is the theory which could have been the Academy. Paris, March 19, 1827. deduced from anatomical investigation : but BARON CUVIER. (Signed) Messrs. Milne Edwards and Audouin, have also established it in the most indisputable manner by their researches, and by the experiments we shall soon mention. By their PHYSIOLOGICAL OBSERVATIONS. anatomical labours, our authors have completely demonstrated the mode of circtilation in three great families of the order of By JAMES CARSON, M.D. Liverpool. crustacea; they have pointed out many errors in works, in other respects greatly esteemed; they have furnished positive proofs Arr explanation of the causes by which of the mode of branchial circulation already the arteries are emptied immediately after mentioned by the authors of the lectures on death, was printed in the illedico-Chirurgicomparative anatomy, and they are the first cal Transactions of London for the year have out and who pointed perfectly appreciated the functions of the venous sinuses, 1820. Many inferences, important in my which present the greatest analogy with the in a pathological, and organs of a similar nature, described by opinion M. Cuvier in certain mollusca, and par- economical view, may be drawn from that ticularly in the sepia loligo. doctrine. A few of these, with a reply to The physiological experiments contained in the first part of this work are undoubt- some objections which have been raised edly of importance, and most likely they against the doctrine itself, will constitute aided Messrs. Edwards and Audouin in the the present communication. discovery of the facts which they have made As the doctrine of the vacuity of the arteknown in so complete a manner ; but the results above mentioned could only be ob- ries after death, as laid down in the paper tained and properly understood, after the exposition of their anatomical investiga- just noticed, may not be familiar or known tions. The principal experiments may be to all the readers of TjiE LANCET, I shall reduced to four. By the first, the authors ascertained that when the liquid contained now briefly repeat the argument by which in the internal or efferent vessel of the it is supported. branchia is drawn out by means of a glass The organs engaged in the circulation of blowpipe, the blood does not fill the vessel the blood anew. The second experiment, which apappear to be of two kinds; the pears more demonstrative, consists tn the first acting from irritability, and the second

by

physiological,