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USES OF THE MODERN MICROSCOPE.
90 to refute his hypothesis ;for how do I know but there may be more in it than I am aware of? A depth of erudition concealed in 11 pabulum" and quasi-glandular" to me unfathomable ! feel, indeed, that I should be guilty of unpardonable presumption were I to make any such attempt, and therefore I am driven to the " lame and impotent conclusion" of simply requesting " Amicus Veritatis" will reconcile his theory with the following fact, that the spleen of a man is one-sixth the weight of the liver, and the spleen of a pig only one-twelfth. When " Amicus Veritatis" has accomplished this, my chief scruple will be removed; and I shall no longer hesitate to acknowledge myself a convert to the ″ quasi-glandular" liypothesis. I am, Sir, your obliged and obe. dient servant, JOHN JACKSON.
The spleen, I have already said, consists and essentially of a venous plexus, which is merely the radicles of the splenohepatic vein. This vein may with propriety be divided into three parts ; the radicles, or the spleen ; the trunk, or splenic and portal vein ; and the branches in the liver, or the sub-hepatic veins. The radicles of the spleno-hepatic vein possess the property of vital contractility (as is proved by the spleen varying in size at different times in the same animal) ; and so do the splenic vein, portal trunk, and branches, as is proved, at least so I conceive, by the latter being surrounded by a sheath of loose cellular membrane, the capsule of Glisson, which is simply a provision to enable them to contain a varying quantity of blood. Now, admitting this to be the use of the capsule of Glisson (and let him who says such is not its use show that it is not, by assigning to it a better one), it is evident that if the spleno-hepatic trunk and branches did not possess, as well as the radicles of the spleno-hepatic vein, or spleen, the property of vital contractility, they (the trunk and branches) never could contain a varying quantity of blood, but would always be distended ; and then, I assert, that not only would Glisson’s capsule be of no kind of use, and that the branches of the splenohepatic vein might, as well as not, have resembled the supra-hepatic veins in being simple canals, but also that the spleen would no longer be an assistant-circulatory organ, would in truth be, as Erasistratus of old affirmed it was, an useless organ,and one which Nature might have spared herself the
try
chiefly
London, Oct. 1, 1842. MODERN MICROSCOPE.
USES OF THE
POINT AT WHICH RELIANCE ON ITS POWERS SHOULD CEASE.—RECENT DISCOVERIES IN ANIMAL ORIGIN AND GROWTH, AND IN THE BRAIN.
THE ultimate structure of the animal organs is so minute as to be only discerned by the aid of the microscope. This instrument in the present day is so universally employed in the investigation both of healthy and diseased structure, and such constant reference is made to it in the works now issuing from the press, that some repains to construct. But it is altogether wrong to regard the marks on its use and the extent to which we spleen merely as an isolated organ, it is, as may safely trust its results, will not probably I have before said, essentially a venous be misplaced at the present time. plexus, the radicles only of the spleno-hepa- . A careful consideration of what has been tic vein, and a part of that vein. We need, accomplished by the microscope, joined to therefore, no longer marvel why its removal some practical acquaintance with its emis unattended by any very serious immedi- ployment, has convinced me that we can only ate consequences ; for we remove only the place implicit reliance on it when it is apradicles of a vein (a part of a vein), and that plied to the investigation of parts which are part the least important, its commencement. of such a magnitude as to be rendered plainly We do not remove the trunk and branches, visible with the assistance of low power, nor do we deprive that trunk and those such as the capillary blood-vessels, the branches of their property of vital contrac - mucous glands, or the blood corpuscles of tility ; and although the portal circulation is, the frog. When high powers are necessary, doubtless, less free and perfect after than be- as in the examination of muscular fibre, fore the removal of the spleen, we have not, magnifying, for instance, from 600 to 1200 thatI can see, a sufficient reason for believ- diameters, where the least alteration in the ing itiat the left ventricle is even then, and light, or the slightest touch of the adjusting under those circumstances, the ageut in the screw, changes the whole aspect of the object, propulsion of the portal blood. uncertainty begins to prevail, conflicting acto all the objections of counts are given, and hence the endless conreplied Having " Amicus Veritatis,’’ I shall conclude, not, troversies, from the bygone times of Leuwenhowever, by endeavouring to refute his hy- hoek, Malpighi, and Fontana, to those of the pothesis, for, to speak truth, I am afraid it present day. Those who wish to be conis above my very limited comprehension. I vinced of the justice of these remarks, may am ashamed to confess that I have yet to refer to an American writer, Dr. Paine,who, learn the meaning of some of the words being beyond the vortex which influences, which he employs, such as " pabulum" and more or less, most of the anatomists of Europe ″ quasi-glandulal.’’ I shall not, therefore, at the presen t moment, has, in a somewhat
I
91
in strong relief the inconsistencies and contradictions of the most distinguished microscopical observers. An instance of the difficulty of determining the ultimate structure by means of the microscope is afforded by the fact, that although by the aid of that instrument, and successful inspection, the most minute ramifications of a blood-vessel can be distinctly seen, we know absolutely nothing of the mechanism by which the secreted fluids, the bile, urine, and so forth, pass out of the blood channels ; and yet pores of some kind there must be, as
Highly important results follow this last discovery of Dr. Barry, especially in relation to the corpuscles of the blood.
hypercritical exposé, placed
the red particles occasionally are extravasated, without a trace of laceration or rupture. Where, then, there are so many sources of ocular deception, we shall all do well to remember the sagacious observation of Hunter, thatas the naked eye, when viewing an object rather too small for it, is not to be trusted, it is much less to be depended upon when viewing an object infinitely smaller, brought to the same magni. tude by a glass." In oliering these remarks, I in no degree wish to underrate the great utility of the microscope when judiciously applied, nor to depreciate the labours of those zealous and even
This is a -brief allusion to one of the most
important additions which has in late years been made to the science of organisation, and although Purkinje, Rosenthal, and Henle,
have somewhat modified the views of Schwann, yet the main facts remain undisturbed. The great truths deducible from the investigation are, first, as regards the anatomy, that all organic bodies, animal and vegetable, assume precisely the same form in their first development; whilst with respect to physiology, it is proved that the part of the cell called the nucleus, has the power of multiplying itself by division, and thus of in.
creasing indefinitely. ,
In order that you may obtain
a more
de-
finite idea of the utility of microscopic obser’, vation, it may be desirable to select a part with which you are more familiar, namely,
the brain. In the ordinary, and I must add rude manner, in which this organ is dissected, you perceive nothing but a soft, and, in the greatest part of its extent, apparently a homogeneous mass. The admirable Gall talented observers whose researches have so demonstrated the fibrous structure of the much enriched the science of anatomy and brain in all its parts, excepting its grey corphysiology. In fact, if we were to imitate tex ; but here our knowledge, so far as the the example of some writers, and to deter- naked eye was concerned, ended, more subtle mine unphilosophically to reject the micro- means of investigation being required to scope because it has led to occasional errors, detect the true structure of that which conwe must at the same time be content to aban- stitutes the instrument of innervation. don all attempts to determine the ultimate Now let us see what the microscope has and essential structure of the human organi- done towards advancing our acquaintance sation. One or two instances will enable with this the most interesting organ of the you to form some judgment of the value of animal economy. Fontana, whose account these observations. In the first place, the agrees with the most accurate modern rewhole discovery and history of cells, both searches, to an extent which is surprising animal and vegetable, normal and abnormal, when we consider the imperfect instrument are due to the microscope. By the researches he employed, discovered that the nervous of Schleiden and Schwann, the important fibres were tubular, the sheath consisting of fact has been established, that all organic a transparent membranous cylinder, and the tissues, whatever may be their ultimate form, contents, as Fontana supposed, of a gelatiin the beginning consist of cells having essen- nous and consistent humour. Bv more recent tially the same physical character; that by observation it has, however, been established the elongation and subsequent communica- !, that the nervous matter, or neurine,-which tion of these primary cells, tubes are formed, is during life fluid and transparent, the soft, as, for example, the simple ducts of plants solid, and opake character which it presents and the blood-vessels of animals ; whilst by a soon after death, being the result of coagudeposition of solid matter, either within the ’I lation,--may bedistitictly observed with the original cells, or in the canals developed from ’i naked eye in the retina, which, if examined them, the organic solids, as woody fibre, in an animal just killed, is seen to be, as it is bone, and muscle, are formed. Not only doi life, diaphanous, whilst iu a few minutes it all organised ttssues originate from cells, assumes that resemblance to ground-glass but as we learn from the inquiries of Pur- with which we are familiar. But this is not kinje, Barry, and Valentin, even the whole all, for Professor Valentin, in a course of organism itself. These eminent observers observations made upon the nerves of living have ascertained that the embryo or gerl1l animals, believes that he had detected on is developed from a cell called the germinal the inner aspect of the membranous tube of vesicle, or, as Dr. Barry contends, from what is termed the germinal spot, which, by an in* This may be regarded as an established teresting mode of growth or vegetation, forms new cells in geometrical progression, fact, because it does not rest solely on microincreasing in the ratio of 2, 4, 8, and so scopic examination for the change.
in
on.
92
the nervous fibre a ciliary epithelium." cellular tissue in the production of cancerous This structure cannot at present be regarded growths ; for, as there is such an analogy in as established, but if it should be confirmed the laws which govern the first formation of by a more extended observation, it would vegetables and animals, it is not unreasonfollow that some kind of motion or current of able to suppose that, as in cryptogamic and the nervous fluid is effected by ciliary vascular plants, growth may take place motion. either by the action of cells alone, or by Another important step towards unravel- vessels and cells in conjunction ; so in ing the intimate structure of the brain has scirrhus, fungus, and colloid, the morbid lately been effected, by determining, with the growth may depend on the action and deveaid of the microscope and minute injections, lopment of cells alone, or in combination the disposition of the capillary blood-vessels with the capillary blood-vessels. in the grey matter. Now let me remind you It must, however, be confessed, that at how entirely the prevailing notions respect- present the microscopic investigations of ing the brain would be changed, if its tex- disease have produced but few well-esta ture were to be studied in accordance with blished and generally-recognised truths. the facts just stated ; that is to say, if, in- Even in the case of morbid fluids where, stead of regarding it as a solid body com- d priori, we should have expected more saposed of soft fibres, amply, indeed, supplied tisfactory results, much uncertainty prewith blood, but in a manner altogether un- vails; thus one of the most interesting cirknown, we should consider the cerebrum as cumstances to the medical practitioner, the consisting essentially of an almost infinite unequivocal distinction, namely, between multitude of tubuli filled with fluid. I say mucus and pus, is a desideratum yet to be nothing of their supposed ciliary currents, obtained ; for not only are there diverse dispenetrated by a vast number of arterial and crepancies in the accounts given of the phyvenous canals,carrying, in a definite and ascer- sical characters of the two fluids, by those tained direction, the circulating fluids. It is who admit a distinction between them; but needless to point out the light which views like some eminent authorities, Henle, Barry, these would throw on the pathology of the and Mandl, state that the globules of pus brain, or to show how powerfully they and mucus cannot be distinguished from would illustrate the important views of Dr. each other. In the midst of all this uncertainty, alAbercromby respecting deranged conditions of the cerebral circulation.. though there is no doubt that eventually Before dismissing the subject of micro- most important additions will be made by scopic researches, I may remark, that if cau- the microscope to pathology, it is my duty to tion is required in the case of the healthy point out to you, that as respects disease the organisation, it becomes much more so when results of microscopic observations are at diseased structures are concerned. The itn- present altogether too meagre and unstable portant discoveries respecting cells have un- to lead to any inferences in the actual pracdoubtedly afforded some facts which promise tice of medicine, and still less to justify any interesting results regarding morbid growths; hypothesis as to the proximate cause of for when it is known that a cell can, in vir- disease. tue of its own independent endowments, take From this rapid survey of the means best up, from a surrounding fluid, peculiar sub- adapted to promote the study of anatomical stances, and increase in the manner noticed, science this great truth may be gatheredso as to give rise to the various organised that although Nature displays an almost intissues, woody fibre, bone, or muscle, we can finite variety in the secondary formations of at all events understand that, owing to some animal bodies, yet the primary and essential derangement of these processes, morbid mat- types are few in number and definite in chaters may be produced or taken up, and ab- racter, and that every organ, simple or comnormal cells generated ; phenomena which, plex, animal or vegetable, is constructed in according to Miiller and others, do take obedience to these typical forms. To this, place in carcimonatous tumours, and in the great principle of the organic world, tubercle, according to Gulliver. It is also anatomy, zoology, and geology equally tes probable that the information we have ac- tify : the anatomist proves it by an analysis quired from the physiology of cells will ulti- of the internal formation and arrangement; mately tend to explain many of the appa- the zoologist by the investigation of the exrently conflicting views of Hodgkin, Cruveil- ternal configuration ; the geologist by an aphier, Wiiller, and others, concerning the re- peal to that vast multitude of organic beings spective influence of the blood-vessels and which, imbedded in the stratified crust of our planet, become the silent but unerring ’* This observation is, to a certain degree, witnesses of the remotest acts of creative corroborated by Bemak, who has described power. Guided by this fixed and undeviatthe ciliary motion in nerves, but he places it ing law, the anatomist, proceeding from in the sheath of the primitive bundle, or fas- simple to complex, from the known to the ciculus, not, as Valentin describes it, within unknown, introduces a degree of certainty into the study of organisation, which pro,the sheath of the ultimate fibre itself.
93
mises to raise it almost to the level of the exact sciences; whilst the naturalist, marking the analogies and affinities which link together the various classes, orders, and genera, demonstrates the truth of that circular system of arrangement which, originating in Lamarck, and established by Mr. Leay, joins in one uniform and harmonious whole the apparently diversified and heterogenous members of the animal kingdom.Mr. Grainger’s Lecture, Oct. lst.
glandular organs,
however
complex they
may be, and it was by appealing to the natural analysis so presented to the observer, that Professor Mutler, following in the steps of the illustrious Malpighi, was mainly enabled to solve those conflicting opinions concerning the minute glandular texture which have divided the schools since the times of Ruysch and his contemporaries, and which could never have been satisfactorily determined by the examination of the human body
alone.
I may, perhaps, be allowed to adduce one other illustration in support of the position I have advanced. Suppose the student is OF THE anxious to understand the essential character MEDICAL USES OF COMPARATIVE of the skull, and for that purpose refers to ANATOMY. works on anatomy, he will read that there are cranial vertebrae, and that the skull is I may observe, with respect to comparative constructed on the same principles as the anatomy, that its great utility rests upon the spinal column; but so long as he confines his fact that the various organs of the human observations to the human skeleton, he will body, however dissimilar, in the adult con- be puzzled to make out the identity which dition, may be;theirform and outward appear- really exists between the proper bones of the ance, display, when they are inspected at cranium and the vertebras of the spine. If, an early epoch of their growth, a type of however, he proceeds to the lowest of the formation identical with that of the animal vertebrated animals or fishes, where, as kingdom, and which, with the exception of might be expected, the type of the whole a few and readily explained instances, they vertebrated division first makes its appearretain throughout the whole period of exist- ance, he will find that the great disproporIn virtue of this great law of the tion in size between the cranial and vertebral ence. animal creation, we are enabled by a judi- cavities disappears, the two assuming the cious selection of those classes of animals form of a continuous uniform canal, whilst which exhibit the simplest structure, to seize the bones are less dissimilar than in the the essential typical form of organs, which, classes above. A more searching investigain man, although fashioned on the same tion would enable the inquirer to test more model, are obscured by their amazing iutri- accurately the correctness of the theory of cacy. As an example of the information Frank, Goethe, and others, respecting the which may by these means be acquired, the cranial vertebrae: thus, in the common lamglands may be selected. Among these prey, belonging to the cyclostomatous fishes, organs the liver in the human being is pre- instead of the head being separated from the eminently distinguished by the complexity spine in the customary manner, that is to of its constituent parts ; but in several of the say, where the riug of the atlas approximates mollusca it is reduced to so simple a condi- to the cuneiform process, there is a perfect tion, that the secreting canals can be readily continuity between the cartilaginous subinflated from the main duct; whilst in the stance, the chorda dorsalis, which in this decapod crustacea, as in the lobster, we can, animal forms the spinal column, and that by agitating a small portion of liver in part of the skull which represents the basilar water, easily perceive the coeca of which it process of the occipital bone ; this disposiis composed ; in some other animals the tion, taken in combination with the fact that organ is even reduced to a more simple state, in the human embryo the skull and vertebral as in the biliary tubuli of insects, and in column are originally perfectly continuous, those coecal sacs opening into the stomach of gives consistency and support to what might the asterias, or star-fish, which are believed to otherwise be regarded as the crude speculabe of a secreting nature. The pancreas, again, tions of a philosopher, or the dreams of a which, in man, is a firm conglomerate mass, poet. I need say no more of the importance of presents itself in fishes as a collection of large blind canals, closed at the ends dis- comparative anatomy as illustrating the true tant from the intestine, and by tracing this character of the human orbanisation.-Mr. organ through the gasteropod and cephalo- Urctirryer’s Introductory Lecture, Oct. lst. pod mollusca, we find it passing from an aggregation of tubuli to a form evidently STATni; OF BICHAT. An iron statue in identical with the pancreatic body of mammalia and man. memory of this distinguished physiologist is Now, in the two instances of the liver and about to be erected in one of the squares of pancreas which we have thus briefly no- Bourg. The work is entrusted to M. David, ticed, we detect the essential character of all of Angers.
ILLUSTRATIONS
-
The spleen, I have already said, consists and essentially of a venous plexus, which is merely the radicles of the splenohepatic vein. This vein may with propriety be divided into three parts ; the radicles, or the spleen ; the trunk, or splenic and portal vein ; and the branches in the liver, or the sub-hepatic veins. The radicles of the spleno-hepatic vein possess the property of vital contractility (as is proved by the spleen varying in size at different times in the same animal) ; and so do the splenic vein, portal trunk, and branches, as is proved, at least so I conceive, by the latter being surrounded by a sheath of loose cellular membrane, the capsule of Glisson, which is simply a provision to enable them to contain a varying quantity of blood. Now, admitting this to be the use of the capsule of Glisson (and let him who says such is not its use show that it is not, by assigning to it a better one), it is evident that if the spleno-hepatic trunk and branches did not possess, as well as the radicles of the spleno-hepatic vein, or spleen, the property of vital contractility, they (the trunk and branches) never could contain a varying quantity of blood, but would always be distended ; and then, I assert, that not only would Glisson’s capsule be of no kind of use, and that the branches of the splenohepatic vein might, as well as not, have resembled the supra-hepatic veins in being simple canals, but also that the spleen would no longer be an assistant-circulatory organ, would in truth be, as Erasistratus of old affirmed it was, an useless organ,and one which Nature might have spared herself the
try
chiefly
London, Oct. 1, 1842. MODERN MICROSCOPE.
USES OF THE
POINT AT WHICH RELIANCE ON ITS POWERS SHOULD CEASE.—RECENT DISCOVERIES IN ANIMAL ORIGIN AND GROWTH, AND IN THE BRAIN.
THE ultimate structure of the animal organs is so minute as to be only discerned by the aid of the microscope. This instrument in the present day is so universally employed in the investigation both of healthy and diseased structure, and such constant reference is made to it in the works now issuing from the press, that some repains to construct. But it is altogether wrong to regard the marks on its use and the extent to which we spleen merely as an isolated organ, it is, as may safely trust its results, will not probably I have before said, essentially a venous be misplaced at the present time. plexus, the radicles only of the spleno-hepa- . A careful consideration of what has been tic vein, and a part of that vein. We need, accomplished by the microscope, joined to therefore, no longer marvel why its removal some practical acquaintance with its emis unattended by any very serious immedi- ployment, has convinced me that we can only ate consequences ; for we remove only the place implicit reliance on it when it is apradicles of a vein (a part of a vein), and that plied to the investigation of parts which are part the least important, its commencement. of such a magnitude as to be rendered plainly We do not remove the trunk and branches, visible with the assistance of low power, nor do we deprive that trunk and those such as the capillary blood-vessels, the branches of their property of vital contrac - mucous glands, or the blood corpuscles of tility ; and although the portal circulation is, the frog. When high powers are necessary, doubtless, less free and perfect after than be- as in the examination of muscular fibre, fore the removal of the spleen, we have not, magnifying, for instance, from 600 to 1200 thatI can see, a sufficient reason for believ- diameters, where the least alteration in the ing itiat the left ventricle is even then, and light, or the slightest touch of the adjusting under those circumstances, the ageut in the screw, changes the whole aspect of the object, propulsion of the portal blood. uncertainty begins to prevail, conflicting acto all the objections of counts are given, and hence the endless conreplied Having " Amicus Veritatis,’’ I shall conclude, not, troversies, from the bygone times of Leuwenhowever, by endeavouring to refute his hy- hoek, Malpighi, and Fontana, to those of the pothesis, for, to speak truth, I am afraid it present day. Those who wish to be conis above my very limited comprehension. I vinced of the justice of these remarks, may am ashamed to confess that I have yet to refer to an American writer, Dr. Paine,who, learn the meaning of some of the words being beyond the vortex which influences, which he employs, such as " pabulum" and more or less, most of the anatomists of Europe ″ quasi-glandulal.’’ I shall not, therefore, at the presen t moment, has, in a somewhat
I
91
in strong relief the inconsistencies and contradictions of the most distinguished microscopical observers. An instance of the difficulty of determining the ultimate structure by means of the microscope is afforded by the fact, that although by the aid of that instrument, and successful inspection, the most minute ramifications of a blood-vessel can be distinctly seen, we know absolutely nothing of the mechanism by which the secreted fluids, the bile, urine, and so forth, pass out of the blood channels ; and yet pores of some kind there must be, as
Highly important results follow this last discovery of Dr. Barry, especially in relation to the corpuscles of the blood.
hypercritical exposé, placed
the red particles occasionally are extravasated, without a trace of laceration or rupture. Where, then, there are so many sources of ocular deception, we shall all do well to remember the sagacious observation of Hunter, thatas the naked eye, when viewing an object rather too small for it, is not to be trusted, it is much less to be depended upon when viewing an object infinitely smaller, brought to the same magni. tude by a glass." In oliering these remarks, I in no degree wish to underrate the great utility of the microscope when judiciously applied, nor to depreciate the labours of those zealous and even
This is a -brief allusion to one of the most
important additions which has in late years been made to the science of organisation, and although Purkinje, Rosenthal, and Henle,
have somewhat modified the views of Schwann, yet the main facts remain undisturbed. The great truths deducible from the investigation are, first, as regards the anatomy, that all organic bodies, animal and vegetable, assume precisely the same form in their first development; whilst with respect to physiology, it is proved that the part of the cell called the nucleus, has the power of multiplying itself by division, and thus of in.
creasing indefinitely. ,
In order that you may obtain
a more
de-
finite idea of the utility of microscopic obser’, vation, it may be desirable to select a part with which you are more familiar, namely,
the brain. In the ordinary, and I must add rude manner, in which this organ is dissected, you perceive nothing but a soft, and, in the greatest part of its extent, apparently a homogeneous mass. The admirable Gall talented observers whose researches have so demonstrated the fibrous structure of the much enriched the science of anatomy and brain in all its parts, excepting its grey corphysiology. In fact, if we were to imitate tex ; but here our knowledge, so far as the the example of some writers, and to deter- naked eye was concerned, ended, more subtle mine unphilosophically to reject the micro- means of investigation being required to scope because it has led to occasional errors, detect the true structure of that which conwe must at the same time be content to aban- stitutes the instrument of innervation. don all attempts to determine the ultimate Now let us see what the microscope has and essential structure of the human organi- done towards advancing our acquaintance sation. One or two instances will enable with this the most interesting organ of the you to form some judgment of the value of animal economy. Fontana, whose account these observations. In the first place, the agrees with the most accurate modern rewhole discovery and history of cells, both searches, to an extent which is surprising animal and vegetable, normal and abnormal, when we consider the imperfect instrument are due to the microscope. By the researches he employed, discovered that the nervous of Schleiden and Schwann, the important fibres were tubular, the sheath consisting of fact has been established, that all organic a transparent membranous cylinder, and the tissues, whatever may be their ultimate form, contents, as Fontana supposed, of a gelatiin the beginning consist of cells having essen- nous and consistent humour. Bv more recent tially the same physical character; that by observation it has, however, been established the elongation and subsequent communica- !, that the nervous matter, or neurine,-which tion of these primary cells, tubes are formed, is during life fluid and transparent, the soft, as, for example, the simple ducts of plants solid, and opake character which it presents and the blood-vessels of animals ; whilst by a soon after death, being the result of coagudeposition of solid matter, either within the ’I lation,--may bedistitictly observed with the original cells, or in the canals developed from ’i naked eye in the retina, which, if examined them, the organic solids, as woody fibre, in an animal just killed, is seen to be, as it is bone, and muscle, are formed. Not only doi life, diaphanous, whilst iu a few minutes it all organised ttssues originate from cells, assumes that resemblance to ground-glass but as we learn from the inquiries of Pur- with which we are familiar. But this is not kinje, Barry, and Valentin, even the whole all, for Professor Valentin, in a course of organism itself. These eminent observers observations made upon the nerves of living have ascertained that the embryo or gerl1l animals, believes that he had detected on is developed from a cell called the germinal the inner aspect of the membranous tube of vesicle, or, as Dr. Barry contends, from what is termed the germinal spot, which, by an in* This may be regarded as an established teresting mode of growth or vegetation, forms new cells in geometrical progression, fact, because it does not rest solely on microincreasing in the ratio of 2, 4, 8, and so scopic examination for the change.
in
on.
92
the nervous fibre a ciliary epithelium." cellular tissue in the production of cancerous This structure cannot at present be regarded growths ; for, as there is such an analogy in as established, but if it should be confirmed the laws which govern the first formation of by a more extended observation, it would vegetables and animals, it is not unreasonfollow that some kind of motion or current of able to suppose that, as in cryptogamic and the nervous fluid is effected by ciliary vascular plants, growth may take place motion. either by the action of cells alone, or by Another important step towards unravel- vessels and cells in conjunction ; so in ing the intimate structure of the brain has scirrhus, fungus, and colloid, the morbid lately been effected, by determining, with the growth may depend on the action and deveaid of the microscope and minute injections, lopment of cells alone, or in combination the disposition of the capillary blood-vessels with the capillary blood-vessels. in the grey matter. Now let me remind you It must, however, be confessed, that at how entirely the prevailing notions respect- present the microscopic investigations of ing the brain would be changed, if its tex- disease have produced but few well-esta ture were to be studied in accordance with blished and generally-recognised truths. the facts just stated ; that is to say, if, in- Even in the case of morbid fluids where, stead of regarding it as a solid body com- d priori, we should have expected more saposed of soft fibres, amply, indeed, supplied tisfactory results, much uncertainty prewith blood, but in a manner altogether un- vails; thus one of the most interesting cirknown, we should consider the cerebrum as cumstances to the medical practitioner, the consisting essentially of an almost infinite unequivocal distinction, namely, between multitude of tubuli filled with fluid. I say mucus and pus, is a desideratum yet to be nothing of their supposed ciliary currents, obtained ; for not only are there diverse dispenetrated by a vast number of arterial and crepancies in the accounts given of the phyvenous canals,carrying, in a definite and ascer- sical characters of the two fluids, by those tained direction, the circulating fluids. It is who admit a distinction between them; but needless to point out the light which views like some eminent authorities, Henle, Barry, these would throw on the pathology of the and Mandl, state that the globules of pus brain, or to show how powerfully they and mucus cannot be distinguished from would illustrate the important views of Dr. each other. In the midst of all this uncertainty, alAbercromby respecting deranged conditions of the cerebral circulation.. though there is no doubt that eventually Before dismissing the subject of micro- most important additions will be made by scopic researches, I may remark, that if cau- the microscope to pathology, it is my duty to tion is required in the case of the healthy point out to you, that as respects disease the organisation, it becomes much more so when results of microscopic observations are at diseased structures are concerned. The itn- present altogether too meagre and unstable portant discoveries respecting cells have un- to lead to any inferences in the actual pracdoubtedly afforded some facts which promise tice of medicine, and still less to justify any interesting results regarding morbid growths; hypothesis as to the proximate cause of for when it is known that a cell can, in vir- disease. tue of its own independent endowments, take From this rapid survey of the means best up, from a surrounding fluid, peculiar sub- adapted to promote the study of anatomical stances, and increase in the manner noticed, science this great truth may be gatheredso as to give rise to the various organised that although Nature displays an almost intissues, woody fibre, bone, or muscle, we can finite variety in the secondary formations of at all events understand that, owing to some animal bodies, yet the primary and essential derangement of these processes, morbid mat- types are few in number and definite in chaters may be produced or taken up, and ab- racter, and that every organ, simple or comnormal cells generated ; phenomena which, plex, animal or vegetable, is constructed in according to Miiller and others, do take obedience to these typical forms. To this, place in carcimonatous tumours, and in the great principle of the organic world, tubercle, according to Gulliver. It is also anatomy, zoology, and geology equally tes probable that the information we have ac- tify : the anatomist proves it by an analysis quired from the physiology of cells will ulti- of the internal formation and arrangement; mately tend to explain many of the appa- the zoologist by the investigation of the exrently conflicting views of Hodgkin, Cruveil- ternal configuration ; the geologist by an aphier, Wiiller, and others, concerning the re- peal to that vast multitude of organic beings spective influence of the blood-vessels and which, imbedded in the stratified crust of our planet, become the silent but unerring ’* This observation is, to a certain degree, witnesses of the remotest acts of creative corroborated by Bemak, who has described power. Guided by this fixed and undeviatthe ciliary motion in nerves, but he places it ing law, the anatomist, proceeding from in the sheath of the primitive bundle, or fas- simple to complex, from the known to the ciculus, not, as Valentin describes it, within unknown, introduces a degree of certainty into the study of organisation, which pro,the sheath of the ultimate fibre itself.
93
mises to raise it almost to the level of the exact sciences; whilst the naturalist, marking the analogies and affinities which link together the various classes, orders, and genera, demonstrates the truth of that circular system of arrangement which, originating in Lamarck, and established by Mr. Leay, joins in one uniform and harmonious whole the apparently diversified and heterogenous members of the animal kingdom.Mr. Grainger’s Lecture, Oct. lst.
glandular organs,
however
complex they
may be, and it was by appealing to the natural analysis so presented to the observer, that Professor Mutler, following in the steps of the illustrious Malpighi, was mainly enabled to solve those conflicting opinions concerning the minute glandular texture which have divided the schools since the times of Ruysch and his contemporaries, and which could never have been satisfactorily determined by the examination of the human body
alone.
I may, perhaps, be allowed to adduce one other illustration in support of the position I have advanced. Suppose the student is OF THE anxious to understand the essential character MEDICAL USES OF COMPARATIVE of the skull, and for that purpose refers to ANATOMY. works on anatomy, he will read that there are cranial vertebrae, and that the skull is I may observe, with respect to comparative constructed on the same principles as the anatomy, that its great utility rests upon the spinal column; but so long as he confines his fact that the various organs of the human observations to the human skeleton, he will body, however dissimilar, in the adult con- be puzzled to make out the identity which dition, may be;theirform and outward appear- really exists between the proper bones of the ance, display, when they are inspected at cranium and the vertebras of the spine. If, an early epoch of their growth, a type of however, he proceeds to the lowest of the formation identical with that of the animal vertebrated animals or fishes, where, as kingdom, and which, with the exception of might be expected, the type of the whole a few and readily explained instances, they vertebrated division first makes its appearretain throughout the whole period of exist- ance, he will find that the great disproporIn virtue of this great law of the tion in size between the cranial and vertebral ence. animal creation, we are enabled by a judi- cavities disappears, the two assuming the cious selection of those classes of animals form of a continuous uniform canal, whilst which exhibit the simplest structure, to seize the bones are less dissimilar than in the the essential typical form of organs, which, classes above. A more searching investigain man, although fashioned on the same tion would enable the inquirer to test more model, are obscured by their amazing iutri- accurately the correctness of the theory of cacy. As an example of the information Frank, Goethe, and others, respecting the which may by these means be acquired, the cranial vertebrae: thus, in the common lamglands may be selected. Among these prey, belonging to the cyclostomatous fishes, organs the liver in the human being is pre- instead of the head being separated from the eminently distinguished by the complexity spine in the customary manner, that is to of its constituent parts ; but in several of the say, where the riug of the atlas approximates mollusca it is reduced to so simple a condi- to the cuneiform process, there is a perfect tion, that the secreting canals can be readily continuity between the cartilaginous subinflated from the main duct; whilst in the stance, the chorda dorsalis, which in this decapod crustacea, as in the lobster, we can, animal forms the spinal column, and that by agitating a small portion of liver in part of the skull which represents the basilar water, easily perceive the coeca of which it process of the occipital bone ; this disposiis composed ; in some other animals the tion, taken in combination with the fact that organ is even reduced to a more simple state, in the human embryo the skull and vertebral as in the biliary tubuli of insects, and in column are originally perfectly continuous, those coecal sacs opening into the stomach of gives consistency and support to what might the asterias, or star-fish, which are believed to otherwise be regarded as the crude speculabe of a secreting nature. The pancreas, again, tions of a philosopher, or the dreams of a which, in man, is a firm conglomerate mass, poet. I need say no more of the importance of presents itself in fishes as a collection of large blind canals, closed at the ends dis- comparative anatomy as illustrating the true tant from the intestine, and by tracing this character of the human orbanisation.-Mr. organ through the gasteropod and cephalo- Urctirryer’s Introductory Lecture, Oct. lst. pod mollusca, we find it passing from an aggregation of tubuli to a form evidently STATni; OF BICHAT. An iron statue in identical with the pancreatic body of mammalia and man. memory of this distinguished physiologist is Now, in the two instances of the liver and about to be erected in one of the squares of pancreas which we have thus briefly no- Bourg. The work is entrusted to M. David, ticed, we detect the essential character of all of Angers.
ILLUSTRATIONS
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