376 HAVE FISHES MEMORY. 



Fortunately observations on man and the other mammals for ana- 

 tomic and physiologic purposes have at least taught us that there is a 

 fixed point of departure, that definite questions may be addressed to 

 the object under observation. In the first place, it is known that cer- 

 tain portions of the brain are missing in certain animals and appear 

 in certain others, usually of a higher order, and that their presence 

 implies enlarged capacity in certain directions. In fact, science is 

 to-day in a position to prove that given ganglia and sets of fibers are 

 fitted to serve as the physical basis of certain psychic activities. For 

 instance, in all animals a set of fibers, the optical nerve, issuing from 

 the complicated apparatus of the eye, which receives impressions from 

 the outer world, enters the brain. Uniformly it ends in a part of the 

 brain alike in all. Experience teaches that whether the e3'e, or the 

 optical nerve, or the portion of the brain in which it ends is destroyed, 

 the power of sight goes with it. To this primary visual apparatus, as 

 it may be called, a second is joined in man and the other mammals. 

 Heavy sets of fibers run from a great lobe of the cerebrum to the ter- 

 minal spots of the nerves of vision. The ends of this strand of fibers 

 become closely interwoven with the ends of the nerves that receive the 

 impression of light. A second visual mechanism thus connects itself 

 Avith the first. Its significance has been discovei:ed. If, by way of 

 experiment, the continuity of the second set of fibers is broken, the 

 animals so treated lose, not the ability to sec, but in a measure the 

 ability to recognize what they see. A dog in this condition, even if he 

 suffers hunger, fails to snatch meat held before his eyes though he 

 obviously sees it, and he does snatch it if he can recognize it with his 

 nose, or if one of his eyes has been left intact. 



Not only in the case of vision, but in the case of a number of other 

 functions, the science of the last few decades has developed the fact 

 that at least two central apparatus exist — a primary apparatus indis- 

 pensable for a given function, and a secondary apparatus joined to the 

 former. Concerning the secondary apparatus we know its importance 

 in the execution of acquired movements and in the recognition of 

 objects perceived on a previous occasion. Anatomically it originates 

 in the cortical substance of the brain. In man and the higher animals 

 various parts of the cortex are connected with one another in such 

 manifold ways that it was natural for the assumption to gain currency 

 that the cortex of the cerebrum is the anatomical foundation from which 

 proceed the most varied perceptions, associations, and coordinations, 

 that it is the seat of the higher psychic functions, above all, of the 

 faculty of memory. The theory was greatly strengthened when experi- 

 ment demonstrated that each and every part of the cortex does not 

 appear in animals of all orders. The amphibious animals and the rep- 

 tiles possess only cortical tracts, connected with the primary terminal 

 places of the nerve system of smell. Only when birds are reached do we 



