OF THE BRAIN AND NERVES. 163 



The spleen seems not to have any immediate connexion with life. 

 It can only be classed with the extreme parts of the body ; for animals 

 can go on as well, to all appearance, without it, as those that have it. 

 The common use assigned to it seems to have no foundation, as it is of 

 so veiy trifling a size in some animals. In the lizard it is not half the 

 size of one of the testicles. In fowls it is in the middle of the body, 

 and therefore it cannot be formed for a balance to the liver. 



Of the Oil or Fat. 

 The oil or fat of an animal increases with age ; but, even in the young 

 animal it would appear that it was necessary that there should be some 

 substance as a substitute for fat ; for in those places where oil is most 

 to be found in the adult, there we find another substance in the young 

 subject. It is not an easy thing to say what this substance is ; it is 

 more or less oily. In the new-born child it is hardly dissolvable with 

 heat, and hardly inflammable ; and is of a greyish white. It is not 

 universal through the interstices of parts, as in the adult. As the animal 

 advances this substance is changed more and more for oil, and becomes 

 more and more dissolvable by heat, more and more inflammable, and 

 also more and more diffused, and of a yellow colour ; for instance, the 

 tallow of an ox, the oil in the [human] feet. 



Of the Brain} and Nerves. 



As the nerves are large in proportion to the size of the brain in the 

 more imperfect animals, and as these animals have life in a greater 

 degree than the more perfect in proportion to the size of brain, we may 

 reasonably suppose that the nerves are the cause of simple life. 



It seems evident that the brain has such power over the nerves as is, 

 in some degree, mechanical ; for the nearer to the brain the nerves [are, 

 they] seem to have more influence, or are stronger in their action ; and, 

 therefore, the medulla is sent down the spine, and the organs of sense 

 are placed in the head ; and in animals whose nose is some way from 

 the brain, the olfactory nerves run a considerable way pulpy, as in the 

 crocodile 2 . 



Injuries of the brain seldom or ever affect immediately the actions of 

 the heart and arteries. The pulse is regular and soft, but often full. 

 The brain would seem to have two powers ; the one, sensation, or a 

 consciousness of the body, by which means it regulates the motions 

 depending upon it ; the other, where it supplies simple life ; for we all 

 know that an animal may live after such injury has been done to 

 the brain so as to take off all sensation, as we see in many fits. 



1 [For Hunter's views of the leading modifications of the brain in the animal 

 series, see p. 29.] 



2 [Hunt. Prep. No. 1315.] 



M 2 



