24(5 THE BRAIN OP^ THE TIGER SALAMANDER 



with the correlation of olfactory with a wide variety of other types of 

 sensory experience, it is equally evident that the type of adjustment 

 made is radically different. To this topic we shall return (p. 252). 



The intricate connections described above are very different from 

 those of the specialized fishes. How they are related with those of 

 mammals remains uncertain, pending further study of intermediate 

 species. The lack of differentiation of a localized mamillary body 

 here is probably explained by the failure of the fibers of the pri- 

 mordial postcommissural fornix to reach the hypothalamus (p. %55) ; 

 and this, in turn, is correlated with the primitive structure of the 

 hippocampal formation. The analysis of the intricate system of post- 

 optic commissures (chap, xxi) probably provides an instructive point 

 of departure for further study of these connections, leading up to a 

 solution of still controversial problems about the mammalian supra- 

 optic commissures. 



The nervous connections of the hypophysis in urodeles are very 

 large, and they are so arranged as to be easily accessible for experi- 

 mental study. It is hoped that advantage will soon be taken of this 

 favorable material for investigation of some problems of endocrinol 



ogy. 



