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and the thalami, as in reptiles and fishes, are round and hollow. The cerebellum is also hollow, and, consisting of but one lobe, has no cerebellar commissure or pons, and the pyramidal and olivary bodies are hardly apparent. Their existence was denied by Cuvier and others; but until Gall and Spurzheim appeared, anatomists were not aware that these, and the restiform bodies, are the rudiments of the cerebrum and cerebellum. The surface of the brain presents no convolutions,-a most important deficiency, and a far more striking characteristic of defect than the comparison of relative size and weight; and they want the commissures called corpus callosum and fornix, and, of course, the septum lucidum and mamillary bodies. But they have, according to Dr Spurzheim, analogous organs of communication. The olfactory tubercles arise from the point of the hemispheres, of which they appear to be a mere continuation. Between the cerebral ganglia, or corpora striata, and thalami, as they are called, there are four roundish bodies, similar to those of fishes, analogous probably to the corpora quadrigemina of mammiferous animals, and, as in them, proportioned to the size of the optic nerves. Birds, like fishes, having no diaphragm, are without phrenic nerves; the nervus accessorius is wanting for a similar reason; and, as might be expected, the facial nerve is hardly developed.

Between the instincts of birds, which, in the gregarious and migratory species, are very remarkable, and their cerebral configurations, Messrs Gall and Spurzheim have discovered a relation. The aquatic differ in this respect from land birds; and of the passeres, the brain of the male, which sings, is different from that of the female, which cannot sing. Again, birds which build nests and provide for their young are unlike the cuckoo and ostrich, whose heads are similar, and in which these instincts are never manifested, and so on through. out the entire range of their propensities. That many birds have intellectual powers is evident from the docility of the parrot, raven, and falcon. The gull, the wild duck, and the

plover, will feign lameness, to lead intruders from their young. And the conduct of the hooded crow (corvus cornix) in obtaining food from the larger shellfish, is perfectly rational. Dr Fleming, who was an eye-witness of its proceedings, thus describes them :-"We have seen the hooded

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crow in Zetland, when feeding on the testaceous mollusca, able to "break some of the tenderer kinds by means of its bill, aided in "some cases by beating them against a stone; but as some of the "larger shells, such as the buckie (buccinum undatum), and the "wilk, cannot be broken by such means, it employs another me"thod by which it accomplishes its object. Seizing the shell in its "claws it mounts up into the air, and then loosing its hold, causes the "shell to fall amongst stones, (in preference to the sand, the wa"ter, or the soil of the ground,) that it may be broken, and give "easier access to the contained animal. Should the first attempt "fail, a second and a third are made, with this difference, that the crow rises higher into the air, in order to increase the power of "the fall, and more effectually remove the barrier to the contained "morsel. On such occasions we have seen a stronger bird remain "an apparently inattentive spectator of the process of breaking "the shell, but coming to the spot with astonishing keenness when "the efforts of its neighbour had been successful, in order to share " in the spoil."*

We now come to the mammalia, between which animals and man there is the nearest resemblance in functions and cerebral development. That brutes, in addition to the senses and instincts, have knowing faculties, is on all hands admitted. "The ox knoweth his owner, and the ass his mas"ter's crib." Nor are they entirely destitute of sentiments, as Cuvier observes. "The affliction many of them feel on "the absence or loss of a companion, friend, or benefactor, "is manifested by evident signs, in the same manner as they "testify their attachment without any temporary induce"ment." Surpassing him in the perfection of the senses and strength of the propensities, their inferiority in intellect and sentiments to man is unquestionable; and yet when we see how feebly these are exerted in some men, and the consequent abuse of the propensities, we may exclaim with the poet,

"Each kindred brute may bid thee blush for shame.”

* Fleming's Phil, of Zoology, vol. i. p. 231,

Corresponding differences are to be found in their respective nervous systems. The nerves of sense in man are palpably smaller; he has a smaller cerebellum and nervous chord; but he surpasses all other animals in the perfection of the brain. It has, indeed, been truly said, "that by taking away, dimi"nishing, or changing proportions, you might form from the hu"man brain that of any other animal; while, on the contrary, "there is none from which you could in like manner construct the "brain of man."* With respect to size, man, according to Sommering, has, without exception, the longest brain in comparison with the nerves that issue from it. The inferiority to the smaller birds in weight, when compared with the body, is not wonderful, when their leanness and natural levity are considered. Indeed, this criterion is in every point of view objectionable; nor is that much better which is founded on the comparison of the cerebrum with the cerebellum and medulla oblongata, these parts and the brain bearing by no means a constant proportion to each other. As to form, the cerebrum of the human subject is elevated, whereas in brutes it is without elevation. It is nearly spherical in man; but in brutes is either oblong, as in herbivorous animals, or triangular, as in the carnivora. The differences in development and structure are no less remarkable. Excepting in the quadrumana, many of whose actions are almost human, and who differ from man to a distance indeed which is immeasurable, Cuvier says, the posterior lobes are wanting, and the anterior ones are imperfect, consisting in many animals of little more than the processus mamillaris or olfactory organ. The thalami or cerebral ganglia are smaller than in man. The convolutions are fewer and shallower, the corpora quadrigemina larger, being proportioned to the superior size of the visual organs, and there is considerably less cortical than medullary matter. "Independ"ently of weight and size, Sommering observed fifteen visible

• Lawrence, p. 195.

"material anatomical differences between the brain of the 66 common tailless ape and that of man."

Among the various orders of mammiferous animals there is the greatest diversity in docility and intelligence, and, as far as has been observed, corresponding differences in cerebral development. Sommering, who divides the brain into two parts, one connected with the senses, the other with the intellectual powers, observes, "Animals of various kinds

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seem to possess a smaller or larger quantity of the latter portion "_of_brain according to the degree of their sagacity and docility." Mr Lawrence says, "The number and kind of intellectual phenomena in different animals correspond closely to the degree of the development of the brain." The large cranium and high forehead of the ourang-outang lift him above his brother monkeys; and he is said, by Dr Elliotson, to be "curious,

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imitative, covetous, social," and to perform many actions usually considered human. "The gradation of organization and of mind passes through the monkey, dog, elephant, horse, to other quadrupeds." Notwithstanding the exaggerated reports of travellers, the superiority of intelligence and adaptation to circumstances in the beaver is, says Blumenbach, beyond dispute; and, according to the tables of Cuvier, there is a marked superiority in the size of his brain. Dogs differ as much from each other in instinct and docility as they do in cerebral development. Compare, for example, the bull-dog and the hound, the hound and the greyhound, the mastiff and the poodle. The crafty fox and the ermine, like the dog, lay up stores for the future; on the contrary, in some of the inferior quadrupeds the instincts are not under the dominion of reason. Thus the hamster breaks the wings of dead birds as well as live ones to prevent their escape. All which is agreeable to the observation of Cuvier, "that "the convolutions become fewer and shallower as the brain "diminishes in size; there are none in the rodentia, none in

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very small brains." As might be expected, the cetacea, having no sense or organ of smelling, have neither olfactory nerves nor processus mamillaris.

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We are indebted to Tiedemann for the attempt to demonstrate the gradual evolution of the nervous system. He has traced its progress from its embryo condition to its maturity, and his observations prove that the developments are commensurate with the manifestations of its functions. Monsieur Serres, also treading in the same path, has ascertained that the several portions are formed in succession. The outline of the spinal chord, he says, is soonest completed, then the crura and corpora quadrigemina, and last of all the cerebellum.* Blumenbach observes, "The human encephalon "undergoes considerable changes after birth, in its entire mass, in the proportions of its parts, and in the texture " and consistency of its substance;" attaining, according to the Wenzels, its full weight before the fifth, and size before the seventh year. "The gradual evolutions of the mental "faculties correspond to these alterations, which indeed ac"cord with the slow development of the human frame in "other respects." In infancy the brain is pulpy, and the proportion of the cortical exceeds that of the medullary matter; and both before and after birth the nerves, which, according to M. Serres, are first perfected, are larger than in the adult. In the latter "the cerebellum is equal in weight "to about the eighth or ninth part of the brain; whereas in "the new-born infant it is not a sixteenth or eighteenth part "of it, with a corresponding difference in the manifestations " of its functions." Dr Spurzheim has ascertained that the spinal marrow has obtained solidity and firmness while the brain is pulpy and devoid of fibres; and thus accounts for the muscular activity of children, and their comparative feebleness of intellect. Again, in old age the brain is actually diminished in size, with a suitable degree of apathy and mental decadency.

Between eminently intellectual individuals and idiots the

Spurzheim's Anat. of Brain.

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