LIGHT REACTIONS OF THE CRIMSON-SPOTTED 

 NEWT, DIEMYCTYLUS VIRIDESCENS 



A. M. REESE 



West Virginia University 



INTRODUCTION 



The following experiments, which are extensive rather than 

 intensive in character, were started with a dozen salamanders 

 obtained in the month of November from the Marine Biological 

 Laboratory at Woods Hole. During the course of the experi- 

 ments, which extended over a period of more than a year, three 

 of the animals escaped, so that some of the later results were 

 obtained with only nine animals; they were obtained from 

 Woods Hole because of their comparative rarity in the neigh- 

 borhood of Morgantown when the work was begun. Later, 

 animals were caught in a local pond and these were also used 

 in the experiments. 



No change in reaction, except in one possible case, was pro- 

 duced by prolonged residence (for a month or more) in a photo- 

 graphic dark room, though it was noted that all of the animals 

 were of a lighter shade of color when first brought from the 

 dark room. ' 



In all but one or two cases the animals were confined in a 

 rectangular glass aquarium, six inches wide by ten inches long, 

 with two or three inches of water. The water was used chiefly 

 for two reasons: because the newts were very much more active 

 in the water than they were in the empty aquarium, and because 

 the water, of course, acted as a heat-screen and practically elim- 

 inated heat as a stimulus. 



A few tests were made without water, with no noticeable 

 difference in reaction except speed; the animals responded two 

 or three times as quickly when in water than they did when in 

 the merely moistened aquarium. 



Observations made upon animals in an evenly illuminated 

 aquarium seemed to show that they have a certain tendency 



