162 PROCEEDINGS OF THE AMERICAN ACADEMY. 



H. Comparison of the Reactions of Eyeless Toads to Heat 



and to Light 192 



I. Experiments to determine the Influence of the Central 



Nervous Organs on the Photic Reactions of Amphibians 195 



III. DISCUSSION and CONCLUSIONS 199 



IV. SUMMARY . '. 205 



V. BIBLIOGRAPHY 206 



I. INTRODUCTION. 



A. Historical. 



Considerable interest has lately centred itself in the study of the 

 behavior of animals under the influence of light, and the results of 

 such studies have been largely used in formulating the various theories 

 which attempt to account for the reactions of organisms after they 

 have been subjected to external stimulation. Among vertebrates the 

 amphibians offer particularly favorable material for such study, as 

 the various species may be used for experimentation in or out of the 

 water ; they are, as a rule, very responsive to photic stimulation and 

 are able to withstand severe operations without serious interference 

 with their reactions. A large amount of work by a number of observers 

 has already been done in the study of light responsiveness, and in the 

 next few pages an attempt is made to summarize the results of those 

 studies, so far as they apply to amphibians. For the sake of clearness 

 this material will be considered from a comparative standpoint rather 

 than in an historical order. 



Amphibians react to light by giving motor responses. This motor 

 reaction to illumination was first recorded by Configliachi and Rusconi 

 ('19). 1 They observed that Porteus anguinus, the blind cave sala- 

 mander of Europe, became restless when exposed to light, and this 

 observation has been confirmed by later observers (Semper, '81 ; 

 Dubois, '90 ; Beer, iOI). 1 Since that time responsiveness to light has 

 been noted in the following genera: Triturus, or Triton (Graber, '83, '84 ; 

 Willem, '91), Necturus (Cope, '89, Reese, ;06), Cryptobranchus (Reese, 

 :06, B. G. Smith, :07), Diemyctylus (Jordan, '93), Spelerpes (Banta and 

 McAtee, :06), Rana (Kiihne, '78» ; Loeb, '90 ; Parker, :03" ; Torelle, 

 :03, Yerkes, :03, :06 • Dickerson, :06 ; Holmes, :06 • Cole, :07), Acris 



1 The numbers in parentheses indicate the year of publication of the 

 article referred to, the title of which is given in full in the "Bibliography " 

 at the end of the paper. An apostrophe indicates an omitted 18 ; a colon, an 

 omitted 19. 



