THE BRAIlSr. 



At the outset we may remark that the whole subject will 

 be studied more profitably if it be borne in mind that — 1. The 

 brain is rather a collection of organs, bound together by the 

 closest anatomical and physiological ties than a single one ; in 

 consequence of which it is quite impossible to understand the 

 normal function of one part without constantly bearing in 

 mind this relationship. This aspect of the subject has not re- 

 ceived the attention it deserves. No one regards the aliment- 

 ary tract as a single organ ; but it is likely that the dependence 

 functionally of one part of the digestive canal upon another 

 is not more intimate than that established in that great collec- 

 tion of organs crowded together and making up the brain. 2. 

 Since the relative size, position, and anatomical connections of 

 the parts that make up the brain are different in different 

 groups of animals, not to speak of the fact that the functions 

 of any part of the brain of an animal, like that of its spinal 

 cord, already alluded to, must depend in great part upon its 

 own and its inherited ancestral experiences, it follows that the 

 greatest caution must be exercised in applying conclusions true 

 of one group of animals to another. 3. It follows from what 

 has been referred to in 1 above, that conclusions based upon the 

 behavior of an animal after section or removal of a part of the 

 brain must be, until at least corrected by other facts, received 

 with some hesitation. 4. It also might be inferred from 1 that 

 it is desirable to study the simpler forms of brain found in the 

 lower vertebrates, in order to prepare for the more elaborate 

 development of the encephalon in the higher mammals and in 

 man. 5. The embryological development of the organ also 

 throws much light upon the whole subject. 



The student will see from these remarks that a sound knowl- 

 edge of the anatomy of the brain and its connections is indis- 

 pensable for a just appreciation of its physiology; nor must 

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