SALAMANDERS AND THEIR BRAINS 7 



corded by the writer and many others are widely scattered, often in 

 fragmentary form, and with confusing diversity in nomenclature and 

 interpretation. As observations have accumulated, gaps in knowledge 

 have been filled, early errors have been corrected, the nomenclature 

 has been systematized, and now, with the addition of considerable 

 new observation here reported, the structure may be viewed as a 

 whole and interpreted in relation with the action system of the living 

 animal. Many of my observations during the last fifty years confirm 

 those of others; and, since references to these are given in the papers 

 cited, this account is not encumbered with them except where they 

 supplement my own experience or deal with questions still in con- 

 troversy. I here describe what I myself have seen, with exceptions 

 explicitly noted. This explains the disproportionate number of refer- 

 ences in the text to my own papers. 



Two genera of urodeles have been studied intensively to find out 

 what is the instrumentation of their simple patterns of behavior. All 

 observations on the brain of the more generalized mudpuppy, 

 Necturus, were assembled in a monograph ('336) and several follow- 

 mg papers. The present work is a similar report upon the brain of the 

 somewhat more specialized tiger salamander. The original plan was 

 to follow this with an examination of the brain of the frog, for which 

 abundant material was assembled and preliminary surveys were 

 made; but this research, which is urgently needed, must be done by 

 others. 



In this book the anatomical descriptions are arranged in such a 

 way as to facilitate interpretation in terms of probable physiological 

 operation. Though the amount of experimental evidence about the 

 functions of the internal parts of the amphibian brain is scanty, there 

 is, fortunately, a wealth of such observation about the brains of other 

 animals; and where a particular structural pattern is known to be 

 colligated with a characteristic pattern of action, the structure may 

 be taken as an indicator of the function. The reliability of this meth- 

 od depends upon the adequacy of our knowledge of both the function 

 and the structure. The present task, then, is an assembly of the 

 anatomical evidence upon which the interpretations are based. 



The first part of this work is written to give biologists and psy- 

 chologists an outline of the plan of organization of a generalized 

 vertebrate brain and some insight into the physiological principles 

 exemplified in its action. These eight chapters, with the accompany- 

 ing illustrations, can be read independently of the rest of the book. 



