304 Joii?'}wI of Comparative Neurology and Psychology. 



normal and the decapitated animals, when together or separate, 

 react in the same manner as they do in diffuse dayhght and direct 

 sunlight. They are negatively phototropic. 



In case the normal larvae are unable to escape a bright light 

 they almost invariably orient themselves in such a position that 

 the hght falls with equal intensity upon the two sides of the body. 

 It w^as also noted that in the great majority of cases the heads were 

 turned toward the light. The decapitated individuals showed the 

 same orientation, except that the heads were about as frequently 

 turned from the light as toward it. 



A sharp pencil of rays of either sunlight or electric Hght when 

 thrown on the tail of the normal animal causes a quick response. 

 This indicates that the tail is especially sensitive, which is in 

 agreement with the observations of Dubois on Proteus. In the 

 same manner the decapitated animals respond more readily when 

 the rays are concentrated upon the tail than when they are concen- 

 trated on other parts of the body. 



During the summer of 1902 larvae wxre reared in glass aquaria, 

 beneath which w^ere placed pieces of black, white, red, yellow, 

 green and blue paper. Although a large number of counts were 

 made to determine the percentage over the different colors, at 

 successive intervals, there seemed to be no decided preference for 

 one color over another. A second set of observations, the follow- 

 ing year, seemed to show that by far the highest percentage of 

 larvae were found over the green, whether this was placed on the 

 side of greatest or least diffuse daylight. 



In 1905 the same experiment was repeated with the decapitated 

 larvae, but fifty-two counts showed nothing definite beyond the 

 fact that the larvae were most frequently found on the colors in 

 the half of the spectrum toward the violet end. 



It is of interest here to recall that Dubois ('90, p. 356) says: "I 

 have observed that Proteus, under the same condition as the blinded 

 Triton, shows a preference for the following colors in a decreasing 

 series: first, dark, then red, yellow, green, violet, blue and white 

 light." In the Proteus with normal eyes Dubois found the reac- 

 tion towards the various colors was in the following decreasing 

 series: first, dark, then yellow, then green, red, blue, violet. It 

 should be added that these results were not obtained with mono- 

 chromatic light. 



Concerning the reactions of Amphibia to light, there is some 



