CHAPTER I 

 SALAMANDERS AND THEIR BRAINS 



THE SALAMANDERS 



SALAMANDERS are shy little animals, rarely seen and still more 

 rarely heard. If it were not so, there would be no salamanders at 

 all, for they are defenseless creatures, depending on concealment for 

 survival. And yet the tiger salamander, to whom this book is dedi- 

 cated, is appropriately named, for within the obscurity ol its con- 

 tracted world it is a predaceous and voracious terror to all humbler 

 habitants. 



This salamander and closely allied species have been found to be 

 so well adapted for a wide range of studies upon the fundamental 

 features of growth and differentiation of animal bodies that during 

 the last fifty years there has been more investigation of the structure, 

 development, and general physiology of salamanders than has been 

 devoted to any other group of animals except mankind. The reason 

 for this is that experimental studies can be made with these am- 

 phibians that are impossible or much more difficult in the case of 

 other animals. This is our justification for the expenditure of so much 

 hard work and money upon the study of the nervous system of these 

 insignificant little creatures. 



The genus Amby stoma is widely distributed throughout North 

 America and the tiger salamander, A. tigrinum, is represented by 

 several subspecies. The individuals vary greatly in size and color, 

 and the subspecies have different geographical distribution, with 

 some overlap of range (Bishop, '43). The subspecies, A. tigrinum 

 tigrinum (Green), ranges from New York southward to Florida and 

 westward to Minnesota afid Texas. It has a dark-brown body crossed 

 by bright-yellow stripes, as shown in the lower figure of the Frontis- 

 piece. The species probably was named for these tiger-like markings, 

 not for its tigerish ferocity. The upper figure of the Frontispiece is an 

 adult of a western form, with less conspicuous markings. Other sub- 

 species range as far to the northwest as Oregon and British Columbia. 

 Several other species of Ambystoma are found in the same areas as 

 A. tigrinum. 



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