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ordinary Lemurine condition. That the same finger should be the seat of the wasting influences on both hands and in all Aye-ayes strikes one as a result hardly to be looked for on the hypothesis of the cause of such specific structures propounded by Lamarck: that there should be a peculiar modification of the muscles of the forearm, whereby both flexor sublimit and flexor profundus combine their action upon the same tendon, pulling the probe-like digit, is left unaccounted for. The physiologist finds still more difficulty in accepting the explanation of the way in which the peculiar size, shape, and law of growth of the incisors could be brought about. The action of muscles pressing upon the bony sockets might affect the growth of teeth filling such sockets, but could not change a tooth of limited growth, like the incisors of an ordinary Lemur, into a tooth of uninterrupted growth. Besides, the crowns of both the scalpriform incisors of the Chiromys and the ordinary small incisors of other Lemurines are formed according to their specific shape and size, before they protrude from the gum: they acquire so much development while the animal still derives its sustenance from the mother's milk. In the Ave-aye the chisel or gouge is prepared prior to the action of the forces by which it is to be worked. The great scalpriform front teeth thus appear to be structures foreordained—to be predetermined characters of the grub-extracting Lemur; and one can as little conceive the development of these teeth to be the result of external stimulus or effort, as the development of the tail, or as the atrophy of the digitu* tnedius of both hands. The author had elsewhere tested the Lamarckian hypothesis of transmutation by the phenomena of the dentition of the male Gorilla, and no refutation of his argument had appeared.
There remained then to be seen whether the subsequently propounded hypothesis of " natural selection " would allbrd a better or more intelligible view of the origin of the species called Chiromys madayascariensis. Applying to the Aye-ave the illustration of his hypothesis, as submitted by Mr. Darwin to the Linnean Society *, it mav be admitted that the organization of a Lemur, feeding chiefly on fruits or birds, but sometimes on grubs, is or might become slightly plastic, in the sense of being subject to slight congenital variations of structure. We may also suppose changes to bo in progress in the woods of Madagascar causing tho number of birds to decrease, and the number of insects to increase, especially of those the larva? of which are xylophagous. The effect of this might De that the Lemur would be driven to try to catch more grubs. Ilia organization being slightly plastic, those individuals with the best hearing, the largest front incisors, and the slenderest middle digit, let tho difference be ever so small, would be to that extent favoured, would tend to live longer, and to survive during that time of the year when birds or fruits were scarcest; they would also rear more young, which would tend to inherit these slight peculiarities. "Were the Lemurs to be reduced to this insect-food, those individuals less plastic than the incipient Aye-ave, or not varying in the same way, would become extinct. Acceptors of the hypothesis of "natural selection" may entertain no more doubt that such causes in a thousand generations would produce a marked effect upon tho Lemurine dentition and limbs, adapting the form and structure of the Quadrumane to the catching of wood-boring grubs instead of birds, than that any domesticated quadruped can be improved by selection and careful breeding. But, to the author of tho present communication, the propounding of such plastic possibilities left no sense of any knowledge worth holding as to the origin of the species called Cliiromys madayascariensis, no help to the conception of such origin which was at all worth so wide a departure from actual experience of facts. He knew of no changes in progress in the Island of Madagascar necessitating a special quest of wood-boring larva) by small quadrupeds of the Lemurine or Sciurine types of organization. Birds, fruits, and insects abounded there in the ordinary proportions; and the different forms of Lemuridce there coexisted, with their several minor modifications, zoologically expressed by the generic terms Lichanotus, Propithecus, diiroyaleus, Lemur, and Chiromys.
On tJie Zoological Significance of the Cer'hral and Pedial Characters of Man.
the brain of a male European and Negro, and a cast of the interior of the cranial cavity of a full-grown male Gorilla; also figures of the bones of the feet of the Man and male Gorilla, in plates from his " Memoir on the Osteology of the Gorilla" (Trans. Zool. Soc. vol. v. pi. 11).
The brain of the Gorilla, as exemplified by such cast, is of a narrow-ovate form, with the email end forward; the cerebrum does not extend beyond the cerebellum; viewed with the lower surface of the medulla oblongata horizontal, it does not extend so far back as the cerebellum does. The difference of size between it and a small-sized Negro's brain was exemplified in the subjoined admeasurements:—
Length of cerebrum 4 10 6 8
Breadth of cerebrum 8 9 4 10
Depth (greatest vertical diameter) 2 CJ 4 6
Breadth of cerebellum 3 4 3 7
Length of cerebellum 1 10 2 3
Depth of cerebellum 1 4 1 8
In these admeasurements some deduction from the Gorilla's brain must be made for the thickness of the dura mater and other membranes included in the cast: that of the Negro's brain showed it stript of its membranes; and the admeasurements are from a subject corresponding with the smallest of those figured by Tiedemann in the 'Philosophical Transactions' for 1836, pi. 32, in which the posterior cerebral lobes extend half an inch beyond the cerebellum.
Although in most cases the Negro's brain is less than that of the European, Tiedemann and the author of the present paper had observed individuals of the Negro race in whom the brain was as large as the average one of the Caucasian; and the author concurred with the great physiologist of Heidelberg in connecting with such cerebral development the fact that there had been no province of intellectual activitv in which individuals of the pure Negro race had not distinguished themselves. The contrast between the brains of the Negro and Gorilla, in regard to size, was still greater in respect of the proportional size of the brain to the body—. the weight of a full-grown male Gorilla being one-third more than that of an average-sized Negro.
Passing from this contrast to a comparison of the Gorilla's brain with that of other Quadrumana, the author insisted upon the importance and significance of the much greater difference between the highest ape and lowest man, than existed between any two genera of Quadrumana in this respect; the brain of the Gorilla, in the contraction of the anterior lobes, in the non-development of posterior lobes extending beyond the cerebellum, and in the paucity, symmetry, and relative sizo of the cerebral convolutions, so far as they were indicated in the cast, closely accorded with the brain of the Chimpanzee. From these to the Lemurs the difference of cerebral development shown in any step of the descensive series was insignificant compared with the great and abrupt rise in cerebral development met with in comparing the brain of the Gorilla with that of the lowest of the human races. This difference paralleled the difference in the structure of the lower limbs, especially the foot, in the Gorilla and Man; on which difference, as exemplified in the Chimpanzee and lower apes and monkeys, Cuvier had founded the ordinal grade to which he had assigned the genus Hcmo, under the term Bimana. Tho disposition of the hallux as a hinder thumb, with the concomitant modifications of the tarsal bones, was as strongly marked in the Gorilla as in any lower Quadruniane, and the contrast between the foot-structures of the Gorilla and Negro was as great.
The homologies of the parts in the structure of both brain and foot of the Human and Simial Mammalia being demonstrated, as by Tiedemann* and Cuvierf, no
* "Scrobiculus parvus loco cornu posterioris." (Icones Cerebri Simiamm, fol. p. 14, fig. iii.2.)
t "Pouce libre et opposable au lieu du grand orteil." "L'homme est le seul animal vrahnent bimane et lipede." (Ecgne Animal, i. p. 70.) "Pedes hippocampi m in ores vel ungues, vel calcaria avis, qua; a posterior* corporis callosi tanquam processus duo hypothesis of the cause of these homologies, with their structural gradations and dill Perences, would abrogate the necessity of the zoological disposition of the different members of the animal kingdom in groups of difterent degrees of value. The modification of the human foot having been, in the author's opinion, rightly estimated by Ouvier as of ordinal value, he contended that tho equal or correlative degree of difference shown in the development of the human brain, regard being had to the higher importance of that organ in tho animal frame, necessitated its higher appreciation as a zoological character, and that the now known characters of the Gorilla's brain confirmed the reference of the Bimanous order to the subclass Archencephala.
On the Homologies of the Bones of the Head of the Polypterus niloticus.
By Professor R. Owen, M.D., F.R.S., F.O.S. Preparations and sections of the skull of the FulyptertM were exhibited, showing tho wav and proportions in which the bones of the exo- and endo-skeleton were blended together, more especially the extension of the epeneephalic segment backward freely beneath the overarching roof of dermal bones, from which the super-, ex-, and par-occipitals were distinct. Professor Owen referred to a paragraph in his ' Lectures on Oomparative Anatomy' (vol. ii. p. 130), in reference to the inconstancy of the dermo-cranial bones of the Sturgeon, and the confusion caused by applying to them the names "super-occipital," "par-occipital," or other synonyms of the vertebral elements of tho skull. The same remark applies to jilyptents, Lepidostcits, and many extinct Ganoittei.
On Zoological Provinces. By Sir J. Richardson, F.M.S.
This paper consisted mainly of a single question, "What is a zoological province P A right and full answer would, in the author's opinion, open one avenue to the solution of the origin of species which has occupied the naturalists of this country for several yenrs.
lie referred to the Palmipede group of birds. Tho highest latitudes of the Arctic regions to which man has penetrated arc the native places of the Snow Goose, and of various other members of the family, who, having reared their young in two brief months, speed to the southward and winter on the verge of the tropics. Is this whole space, little less in extent than a hemisphere, to be accounted a zoological district P
Tho rango of tho Whale is not far short; but land-animals have a much less wido distribution. Has every class of tho Vertebrata a different zoological province? and how far are any of them conterminous with the. provinces marked out by botanists P
On certain Modifications in the Structures of Diving Animals.
In the class Mammalia, tho Cetacea were contrasted with the Phocidre, and in the clasB Aves, the Colymbidaj were contrasted with the Cinclidro, as to the degree of modification which their tegumentary, circulatory, and osseous systems had undergone in adaptation to their aquatic habits.
The skin of the Seal was less specially modified than that of the Whale, and the aberrations from the ordinary Mammalian character which its bones and teeth presented were in like manner less marked than those of the animals with which it was compared. The teeth in the order Seals were often irregular as regarded their number, their implantation, and their permanence in the jaw; and the epiphyses of the vertebrae were often slow to unite with the bodies. All these particularities were instances of correlation of growth existing between the skin and
meduUares profleiscuntur, inque fundo cornu postcrioris plieas gracilcs et retroflexas formant, in cerebro Simiarum desunt; nec in cerebro oliorum a me examinatorum mammalium oocurrunt j Homini ergo proprii sunt." (Ib. p. 51.) Both the above propositions are susceptible of flat contradiction on homological grounds, and are, nevertheless, true as zoological characters.
systems ns far removed from ita direct influence as the osseous and dental; and tul these particularities, together with those of the systems with which they were correlated, wore much more marked in the Whales than in the Seals.
The Seals were well provided with intrahepatic venous sinuses, but their reservoirs for arterial blood were far inferior in grade of development to those of tho Cetacea. Little could be said as to difference in tho degreo of patency in the foramen ovale and ductus venosus in the two subjects of comparison, at least so far as tlie Common Seal (Phoca rituUna) and Common Porpess (Phocmna communis) might serve as representatives of the two orders. To the rudiments of the festal vena umbilicalis and ductus Botalli, in both, tho same remark applied.
The stunted salivary glands of the Seals seemed an approximation to tho condition of total absence which wo find in carnivorous Cetacea; and, but that some of the latter class possessed olfactory bulbs, a similar relation might bo said to prevail between these organs also in the two orders.
In both classes alike, the weight of tho brain was high as compared with that of the body: in a young Phoca vitulina Dr. Rolleston had found it to be as 1: 40; in a young Phoca-na communis, as 1 : 00.
Tho bark of the Seal spoke plainly enough to its want of any such arrangement of tho larynx as tho Whales possess; but a recent inspection of a large Seal (Pelar/ius monachus) had shown it to possess an exceedingly strong sphincter mu3cle guarding tho entrance to the respiratory passages, and it might bo conjectured that the niembrano-muscular pouch in connexion with tho nasal passages in the Stemmat opus cristatus was a foreshadowing of the sac so often described in connexion with the Cetacean blow-hole.
Several foetal structures were permanently retained in the Cetacea. The thymus, ns shown by Mr. Turner (Edin. Phil. Trans, xxii. pt. 2), was one of these; certain other remnants of the general formative mass of blastema which surrounds the aorta in tho fcetus, noticed by himself in the 'Natural History Review' for Oct. 1801, furnished a second example; and to these the author would now add a third, in the largest remnant of a Wolffian body, or organ of Giraldes, which he had met with in the class Mammalia. The author proceeded to say that, in the two classes of birds which ho had to contrast, scarcely any such approximations could be traced between tho two sets of structures to be compared.
The modifications in the tibia; of the birds commonlv known as "divers" (Colymbince), and the large intrahepatic venous sinuses which thev, in common with the mammals just spoken of, possessed, were beautiful adaptations to the special habits of these animals; but nothing at all reminding us of these structures would bo found in such a bird as tho Water-Ouzel (Cinclus aquaticus). Indeed, tho soft parts of this bird presented very few points of difference from those of a Redwing [Tardus iliacus) dissected at the same time with it, except in the much greater development of the second pectoral muscle. The large size of this muscle was permanently recorded on the keel of the Ouzel's sternum; and this point might perhaps have enabled us, a priori, to predict that the bird possessed the peculiar habits which have given it its trivial name. This ridge extends the whole length . of the keel in the Water-Ouzel; and in this point, as well as in the lesser relative depth of that process, and in the greater relative breadth of the lateral portions of the sternum, and in its more nearly circumscribed posterior cmarginations, the bird in question differed from allied species of dissimilar habits.
Receivt Experiments on Heterogencsis, or Spontaneous Generation. By James Samuelson. The author communicated the results derived from the simultaneous exposure of various kinds of infusions prepared by him in Hull, Paris, and Liverpool. Amongst those results the following afford fresh evidence against the theory of spontaneous generation, and tend to prove the existence of innumerable germs of life in the atmosphere.
Dr. Dalbiani (the author's coadjutor in Paris) found certain well-defined species of Infusoria in his infusions, whicn he also discovered in the moistened dust from his window; and another well-marked species, found in large numbers by Dr. Balbiani in his infusions in Paris, was traced by Mr. Samuelson, first in moistened dust from the high road near Liverpool, then in dust taken from his own window and washed in distilled water, and lastly even in pure, boiled, distilled water, after it had been exposed a few days in the open air in Liverpool. The author watched and carefully described the development of this species (Cercotnonas acuminata) from its first appearance to its full growth.
On the Function of the Auricular Appendix of the Heart.
The author considered that the well-marked contrivance exhibited in the appendix, such as the presence of carnea) coluninos in this portion only of the auricle, indicated that it subserved some function more important than that usually assigned to it, namely the better mixing up of the blood received from the veins. Three ascertained facts, none of them of much apparent value separately, would, when connected together, give a hint as to what thnt function might be.
The first was that the auricle, though having walls much thinner and weaker than those of the ventricle, was yet able powerfully to distend the hitter.
The second fact was that the auricle, unlike tne ventricle, did not completely empty itself of blood.
The third fact was that the auricular appendix, though placed at a distance from the auriculo-ventricular orifice, yet was the last portion of the auricle to contract.
From these three facts, taken together, Dr. Ashe inferred that the function of the appendix was to ett'ect tho complete distension of the ventricle, notwithstanding the powerful resistance of its thick muscular walls when distended nearly to their utmost. The forco of the appendix would be transmitted to the ventricle by means of the small column of fluid still remaining in the auricle, and this force would be multiplied within the ventricle as many times as tho superficies of the fluid within that chamber exceeded tho surface which would be presented by the superficies of the fluid within the appendix. Against tho walls of the auricular sinus this force would be a minimum, in consequence of the small superficies of the fluid still remaining within it.
To a certain extent the same thing would bo effected by the contraction of the sinus alone, for its force would become multiplied within the ventricle in measure as the superficies of tho fluid in the latter increased in proportion to that in the former, which diminished pari passu; but tho force exerted hy the sinus becomes diminished towards the close of its contraction, just when the maximum effort is required, and would even vanish altogether were it not for the small column of fluid remaining in the auricle. Dr. Ashe regarded tho function of the cameaj columrue as being neither to increase nor to diminish tho strength of the appendix, for either object could be attained with smooth walls—yet botli views had been put forward —-but as being to effect the complete emptying of the appendix, since the force of this organ could not be exerted on the ventricle except by the injection of a considerable quantity of fluid within it. For this contrivance Dr. Ashe suggested the name of " the hydrodvnamic apparatus of tho heart."
Dr. Ashe also consfdered that this powerful distension of the walls of the ventricles might be an operating cause of their contraction, analogous to the view which had been suggested regarding the cause of the contraction of the walls of the uterus at the completion of the period of pregnancy.
On the Function of the Oblique MuscUs of the Eye. By Isaac Ashe, A.B., M.B. The author doubted the view that assigned to theso muscles the function of rotating the eyeball on its antero-posterior axis, never having observed such rotation either incidentally or in experiment. The vision might be directed to any object by the action of the recti alone. The view had been put forward that such rotation was necessary in order tbat