446 Journal of Comparative Neurology and Psychology. 



selachians and becoming more and more conspicuous in am- 

 phibians and especially in reptiles. By reference to fig. 2 one 

 may see how the palaeencephalon persists unchanged underneath 

 the very important neencephalon. 



In the neencephalon of reptiles there appears for the first time, 

 and very definitely, a mechanism which by means of numberless 

 connections within itself provides the possibility for association. 

 In the first rudiment of the cortexthese connections are already so 

 numerous that they can scarcely be overlooked. Even in the 

 lizards the number of associations rendered possible by their net- 

 work is inconceivable. 



'jr^- 



Fig. 2. A cat brain and the brain of Chimaera (see fig. i) combined in order to show the increase 

 resulting from the addition of the neencephalon. 



Investigations which have occupied me for years make it pos- 

 sible to declare with certainty that the oldest cortex becomes con- 

 nected with those parts of the palaeencephalon which serve the 

 sense of smell and the oral sense, and subsequently other cortex 

 regions are gradually superadded to this. 



With the appearance of the neencephalon the behavior of the 

 animal becotfies completely changed. Let us first consider the 

 obtaining of food, because that is the best of the activities to study 

 — indeed the lower animals present to the observer no other form of 

 activity so often as this. We have recognized as the characteristic 

 of the palaeencephalon that when stimulus and disposition are the 

 same, the same activities always result, so that they may be 

 predicted. 



