218 C. JUDSON HERRICK 



The Amphibia, therefore, appear to be the critical types, 

 among existing vertebrates, for the study of the transforma- 

 tions of functional pattern which were effected when the non- 

 olfactory components gradually passed from a subordinate to 

 a dominant position in the architecture of the cerebral hem- 

 isphere. Within this group it is possible to follow the history 

 of this process from generalized and very primitive forms up to 

 the relations in the adult frog, where most of the chief sub- 

 diidsions of the mammalian hemisphere can be recognized. 

 This group possesses the further advantage that the tadpoles 

 begin to function at a very immature stage, whose functional 

 pattern and anatomical organization are being exhaustively 

 investigated by Coghill. The result is that we are able to 

 follow, in the higher amphibian species, the transformation of 

 the cerebral mechanisms from the simplest pattern in the young- 

 est larva to the rather highly elaborated form of the adult in 

 a series of developmental stages each of which is in active func- 

 tion. This offers us very much more favorable material for 

 the em.bryological study of these patterns than in higher verte- 

 brate types whose embryos acquire functional capacity at 

 relatively much later ages. 



Unfortunately, the reflex mechanisms of the Amphibia are 

 still very imperfectly known. I have, accordingly, devoted 

 myself to an analysis of these systems in larval and adult uro- 

 deles. This has necessitated an investigation of their nervous 

 systems in their entirety, from the peripheral end-organs to 

 the highest correlation centers; for the latter can be understood 

 only after the precise functional significance of every fiber tract 

 which enters them has been determined. 



The peripheral nerve components of a number of amphibian 

 species have been carefully described by Strong, Coghill, Norris, 

 and others. Kingsbury ('95) gave an admirable description of 

 some of the central connections of these components in Necturus, 

 and in 1914 I added further details of the functional analysis 

 of the medulla oblongata in Amblystoma. I published also in 

 1914 some observations on the structure and connections of 

 the cerebellum of lower urodeles, particularly Necturus. 



