A CHAMELEON-LIKE CHANGE IN DIEMVCTVLUS. 1 6/ 



When under their normal conditions the salamanders' are of a 

 dirty yellow brown color upon the dorsal surface and a lemon 

 yellow upon the ventral surface. Upon both surfaces there are 

 black pigment spots about one half millimeter in diameter- 

 There are also upon the dorsal surface a number of scattered red 

 pigment spots. This description may apply equally well to ani- 

 mals just taken from their native surroundings or which have 

 been kept in the laboratory for a considerable period at the room 

 temperature. Specimens taken at random from the ponds do not 

 vary much in color. 



When the animals are exposed to a temperature which is much 

 below that to which they have been accustomed it was found 

 that there resulted a change in the appearance of the skin which 

 would continue as long as the low temperature was maintained. 

 Instead of a dirty yellow, the skin assumed a much darker color, 

 becoming dark brown, dark green or in extreme cases almost 

 black. This change took place in the course of a few hours and 

 remained so long as the animals were subjected to the artificial 

 condition. The amount of change in color which took place as 

 the result of the change in temperature was in a measure a func- 

 tion of the total amount of temperature change. If the change 

 were only a slight one the color response would be correspond- 

 ingly slight, while if the temperature change were greater the 

 color change would be also more pronounced. 



If, on the contrary, the temperature of the water in which the 

 animals were living was raised, it was found that the animals 

 responded to the increased temperature by a lightening of the 

 skin. Under these conditions the yellow in the skin became more 

 pronounced and the darker colors less so. This change also was 

 found to continue so long as the water remained warm. When 

 the water became cold the color of the skin would return after a 

 given interval to what it was at the beginning of the experiment. 



Another fact of interest in connection with this color change is 

 that if the temperature of the water be maintained at a constant 

 point and the intensity of the light be changed, the color of the 

 animals will be found to respond in a very definite way. It must 

 be stated, however, that the response in this latter case is less 

 pronounced than that obtained by a change in temperature, and 



