328 NERVOUS SYSTEM. 



physiology, in pathology, and, to a certain extent, the rela- 

 tions clearly shown to exist between the development of in- 

 telligence and certain of the nerve-centres, in different races 

 of men and different individuals. With regard to the location 

 of particular functions in distinct portions of the cerebrum, 

 we have but little definite knowledge, beyond the experi- 

 ments already cited in treating of the irritability of the cere- 

 bral substance, and the probable location of the faculty of 

 speech. The latter point will be fully discussed in its appro- 

 priate place. 



Extirpation of the Cerebrum in Animals. It is, perhaps, 

 sufficiently evident, from anthropological and pathological 

 observations, as well as the study of comparative physiology, 

 that the intellectual faculties reside in the encephalon ; but 

 these methods of investigation do not clearly indicate the 

 special functions of different parts of the cranial contents. 

 We have seen, in our general sketch of the anatomy of the 

 brain, that this is by no means a simple organ, and that cer- 

 tain parts, though they are bound together by commissural 

 fibres, have sufficient anatomical distinctness to lead the 

 physiologist to suppose that they have separate and peculiar 

 properties and functions. One of the most valuable methods 

 of investigation of the functions of these separate ganglia is 

 that of extirpation of one or more, leaving the others, as far 

 as possible, intact. This method was first employed with 

 marked success by Flourens, and has since been adopted by 

 numerous experimenters. It must be remembered, however, 

 that there is no subject of physiological inquiry in which it 

 is so difficult to apply experiments on the inferior animals to 

 the human subject, and none in which the results of experi- 

 ments should be received with greater caution. The reason 

 for this is apparent enough. The brain and the intellectual 

 power of man are so far superior to the development of this 

 organ . and its properties in the lower animals, that some 

 philosophers have regarded the human intelligence as distinct 



