SALAMANDERS AND THEIR BRAINS 1 1 



of cell bodies prove to be most useful for general orientation. Other 

 details can then be filled in by study of reduced silver preparations 

 and especially of Golgi sections. A favorable series of transverse 

 Weigert sections (no. IIC; see p. 3'21) has been chosen as a type or 

 standard of reference, and the median section as reconstructed from 

 this specimen (fig. 2C) has been used as the basis for many diagrams 

 of internal structure. For reference to published figures of this brain 

 and other details concerning it see page 321. Figures 2A and B are 

 similar diagrams of the median section of the specimen from which 

 figures 25-36 were drawn. The topography shown in these median 

 sections is the basis for the descriptive terms used throughout this text. 



Except for scattered references to details, the only systematic 

 descriptions of the brain of Amblystoma are in my papers, Binde- 

 wald's ('14) on the forebrain, and Larsell's ('20, '32) on the cerebel- 

 lum. Mention should also be made of Roofe's account ('35) of the 

 endocranial blood vessels and Dempster's paper ('30) on the endo- 

 lymphatic organ. 



Kingsbury's admirable paper on Necturus in 1895 may be taken as 

 a point of departure for all further investigation of the brains of 

 urodeles, including my monograph of 1933 and several preceding and 

 following papers. Some of the more important descriptions of the 

 brains of other urodeles are cited in the appended bibliography, 

 notably the following: Salamandra (Kuhlenbeck, '21; Kreht, '30), 

 Proteus (Kreht, '31; Benedetti, '33), Cryptobranchus (Benzon, '26), 

 Gymnophiona (Kuhlenbeck, '22), Siren (Rothig, '11, '24, '27), and 

 several other urodeles in Rothig's later papers, Hynobius, Spelerpes, 

 Diemyctylus (Triturus), Cryptobranchus, Necturus. 



For the Anura the excellent description of the frog by E. Gaupp in 

 1899 laid a secure foundation for all subsequent work, and the time is 

 now ripe for a systematic restudy of this brain with the better meth- 

 ods now available and the correlation of the histological structure 

 with physiological experiments specifically designed to reveal the 

 action of this structure. Aronson and Noble ('45) have published an 

 excellent contribution in this field. 



DEVELOPMENT OF THE BRAIN 



No comprehensive description of the development of the brain of 

 Amblystoma has been published. The difficulties met in staging 

 specimens by criteria defined by Harrison, Coghill, and others I 

 have discussed elsewhere ('48, chap. x). Griggs ('10) described with 



