358 



HITCHCOCK'S ANATOMY 



g}yth the weight of the body; in the ox, T }oth; in the fox, 

 ^ -th; while in man it is ^th the weight of the bod jr. 



656. Proportion of the Width of Brain and Spinal 

 Cord in Man and other Mammalia. — This, as well as the 



comparison of cerebral mass and cerebral nerves, between man 

 and other animals, is interesting. The breadth of the spinal 

 marrow is, to that of the breadth of the brain, in man, as 

 1:7; in the dog, as 1 : 2. 



657. Cerebral Nerves. — 1 £ The cerebral nerves correspond 

 to those of man. The first pair, however, forms in some de- 

 gree an exception, for though not absent in all the whale 

 family, it is wanting in the dolphins. In most mammals the 

 olfactory nerves are thick and have a cavity in them. The 

 fifth pair of nerves is, in many mammals, of peculiar strength 

 and thickness when compared with that pair in man." 



658. Sympathetic System. — "The nervous system of 

 organic life— the great sympathetic — is formed, as far as in- 

 vestigations indicate, essentially as in man." It is situated 

 mostly in the cavities of the thorax and abdomen, and follows 

 the course of the blood vessels. 



659. Tentorium. — The tentorium cerebelli, which in man 

 is a simple tough membrane that separates the cerebrum from 

 the cerebellum, is very delicate in some animals, as the horse 

 and dolphin ; while in the cat it is supported by a bony plate 

 springing from the skull, and is a very firm membrane. Its 

 use to protect the brain in those animals whose movements 

 are at times violent and sudden, and especially those that leap 

 great distances. 



660. Spinal Nerves. — The Spinal nerves also, in general 

 appearance, are like those in man. The number of pairs 

 varies in different species, as might be inferred from the dif- 

 fering number of their vertebrae. 



656. State the proportion of the width of the brain and spinal cord. 657. What is said 

 of the cerebral nerves of animals ? 658. What is said of the sympathetic system ? 669. 

 What is said of the tentorium ? 660. What of the spinal nerves of animals ? 



