84 ANN HAVEN MORGAN 



('60) recorded that reflex frogs dosed with strychnia were seized 

 with spasms in a warm room, but became quiet when placed upon 

 ice. A series of investigations followed these early suggestions, 

 actual experiments on the direct and indirect effects of tem- 

 perature upon the central nervous system (Tarchanow, '71; 

 Archangelsky, '73; Freusberg, '75; Wundt, '76), the sensory nerve 

 endings (Heinzmann, '72; Foster, '73; Rosenthal, '75; Sedgwick, 

 '82), and the general behavior of the frog under stimulation by 

 heat and cold. Recent workers upon its responses to light, 

 electricity, sound, chemicals, and temperature have either shown 

 something of its thermic sensitiveness (Koranyi, '92; Parker, 

 '03; Torelle, '03; Yerkes, '06; Pearse, '10) or have suggested the 

 presence of a temperature sense in the skin. But its exclusive 

 presence there, its existence as a separate sense, and the nature 

 of its responses have not been adequately shown. It was with 

 the hope of doing this and of answering the questions already 

 suggested that the present study was undertaken. 



The problem was suggested to me by Prof. G. H. Parker, and 

 it gives me pleasure to express my appreciation of his friendly 

 criticism and constant help. 



HISTORICAL 



Temperature studies upon the frog have covered a wide range 

 of attack. Information regarding the effect of temperature upon 

 the skin has come into the hterature indirectly, usually in connec- 

 tion with special studies of a system of organs or the behavior 

 of the whole organism. In the hope of showing these different 

 aspects with greater clearness, I have discussed them by topics 

 rather than in historical sequence. 



Frogs respond to variations in temperature by visible motor reac- 

 tions. This was established experimentally by Kunde ('60), 

 Cayrade ('64), Goltz ('69), Tarchanow (71, '72), Archangelsky 

 ('73), Rosenthal ('75), Freusberg (75), and Wundt ('76). The 

 means of stimulation were partial or complete immersion in warm 

 or cold water, dipping in warm or cool dilute acid, and ice packs 

 and hot sand baths. From treatment of these kinds one group 

 of workers (Kunde, '60; Richardson, '67; Weir-Mitchell, '67; 



