48 HUMAN PHYSIOLOGY. 



to the three middle toes also. The latissimus dorsi is destitute in Man of that 

 prolongation attached to the olecranon, which is found in the lower Mammalia, 

 and which exists even in the Chimpanzee, probably giving assistance in its climb- 

 ing operations. The larger size of the muscles of the thumb is, as might be ex- 

 rted, a characteristic of the hand of Man ; although the number of muscles 

 which that digit is moved is the same in the Chimpanzee as in the Human 

 subject. The existence of the extensor digiti indicis, however, as a distinct 

 muscle, is peculiar to Man. 



10. The Visceral apparatus of Man presents very few characteristic pecu- 

 liarities, by which it can be distinguished from that of the higher Quadrumana ; 

 among the most remarkable is the absence of the laryngeal pouches, which exist 

 even in the Chimpanzee and Orang Outan, as dilatations of the laryngeal ven- 

 tricles. Of the anatomy of the last-named animals in their adult condition, 

 however, we know as yet too little to enable its conformity to that of Man to be 

 confidently pronounced upon. 



11. The Brain of Man does not differ so much in conformation from that of 

 the Chimpanzee and Orang, as the superiority of his mental endowments might 

 have led us to anticipate. The following are the principal differences which it 

 seems to present : 1. The mass of the entire brain is considerably larger in 

 proportion to that of the body, and in proportion also to the diameter of the 

 nerves which are connected with it. 2. In the external configuration of the 

 Cerebrum, we notice that the posterior lobes are more developed, so as to pro- 

 ject further beyond the Cerebellum than they do in any of the Quadrumana ; 

 the convolutions are more numerous, and the sulci are deeper. 3. On examin- 

 ing the internal structure, it is found that the peripheral layer of gray matter 

 is thicker, the corpus callosum extends further backwards, and the posterior 

 cornua of the lateral ventricles are relatively longer and larger than they are in 

 any Quadrumana. 4. The Cerebellum, also, is proportionally larger. 



12. The small size of the face of Man, compared with that of the cranium, is 

 an indication that in him the senses are subordinate to the intelligence. Accord- 

 ingly we find that while he is surpassed by many of the lower animals in acuteness 

 of sensibility to light, sound, &c. he stands pre-eminent in the power of comparing 

 and judging of his sensations, and of drawing conclusions from them as to their ob- 

 jective sources. Moreover, although none of his senses are very acute in his natu- 

 ral state they are all moderately so, and they are capable of being wonderfully 

 improved by practice, when circumstances strongly call for their exercise. This 

 seems especially the case with the tactile sense, of which Man can make greater use 

 than any other animal, in consequence of the entire freedom of his anterior extre- 

 mities ; although there are many which surpass him in their power of appreciating 

 certain classes of tactile impressions. So again, Man's nervo-muscular power is 

 inferior to that of most other animals of his size ; the full grown Orang, for 

 example, surpasses him both in strength and agility ; and the larger Chimpan- 

 zee, according to the statements of the Negroes who have encountered it, is far 

 more than a match for any single man, and is almost certain to destroy any 

 human opponent once within his grasp. The absence of any natural weapons 

 of offence, and of direct means of, defence, are remarkable characteristics of 

 Man, and distinguish him not only from the lower Mammalia, but also from the 

 most anthropoid Apes j in which it is obvious (both from their habits and gene- 

 ral organization) that the enormous canines have no relation to a carnivorous 

 regimen, but are instruments of warfare. On those animals to which Nature 

 has denied weapons of attack, she has bestowed the means either of passive 

 defence, of concealment, or of flight ; in each of which Man is deficient. Yet, 

 by his superior reason, he has not only been enabled to resist the attacks of 

 other animals, but even to bring them into subjection to himself. His intellect 

 can scarcely suggest the mechanism which his hands cannot frame ; and he has 



