THE NERVOUS SYSTEM OF THE AMERICAN LEOP- 

 ARD FROG, RANA PIPIENS, COMPARED WITH 

 THAT OF THE EUROPEAN FROGS, RANA ESCU- 

 LENTA AND RANA TEMPORARIA (FUSCA). 



HENRY H. DONALDSON. 



(Professor of Neurology at the Wistar Institute?) 

 {From the IVistar Institute of Anatomy and Biology, Philadelphia^ 

 With Six Figures. 



With the advances which are being made in the correlation of 

 function and structure, the need is felt on many sides for a more 

 detailed, accurate and quantitative determination of the anatomical, 

 physiological and chemical differences between closely related 

 species, as well as between the same species from different local- 

 ities. 



The general notion of a physiological and chemical criterion for 

 species has been discussed by de Varigny ('99) and, although 

 this is not the place to review the Hterature touching this topic, 

 it is nevertheless appropriate to name Camerano's paper ('00) 

 on the variation of the toad, which, among his many important 

 contributions in this general field, is the one most closely related 

 to the following investigation. Moreover, Kellicott's recent 

 study of correlation and variation in internal and external charac- 

 ters in the common toad ('07) emphasizes relations which have a 

 direct bearing on the interpretation of my own results. 



In 1898 I made a study of the weight of the brain and of the 

 spinal cord in the bull-frog R. catesbiana (Donaldson '98). 

 Two years later, in collaboration with Dr. D. M. Schoemaker, 



