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PROCEEDINGS OF THE AMERICAN ACADEMY. 



preceding species. There were, however, such differences in the re- 

 actions of the four animals used that they are tabulated separately. 

 Individual No. 1 never failed to move straight toward the light. No. 2 

 was not as persistently positive after the eyes had been excised as be- 

 fore this operation, though it continued to give a majority of positive 

 reactions. As individuals 3 and 4 were apparently indifferent to the 

 light in their normal conditions, their eyes were not removed. The 

 reactions of animals 1 and 2 were, however, strongly positive, and this 

 condition remained even after the eyes had been excised ; hence their 

 skins served as photoreceptors as well as their eyes. 



(h) Bufo americanus and B. fowleri. 



Both these species were used for experimentation, but, as the records 

 were not kept separate, their reactions cannot be distinguished and 

 are given together in Table VI. The results include experiments with 



TABLE VI. 



Photic Reactions of Normal and Eyeless Toads. 



twenty normal animals and six in which the eyes had been excised. In 

 removing the eyes from another individual, the head was cut diagonally 

 so that the left ear was injured. This animal turned continually to the 

 right, regardless of the direction of the light, and its reactions were 

 therefore not included in the table. Although most of the individuals 

 were adults, a few were immature, but none of them measured less than 

 two centimeters in length. The results show the species to be positively 

 phototropic in response to stimulation received through the skin as well 

 as through the eyes. 



It was also possible to show that the phototropic reactions of eyeless 

 toads were not due to the effect of light upon the exposed ends of the 

 optic nerves. On two occasions, after an individual had given ten 

 successive positive responses, it was immediately oriented in such a 

 manner that the anterior end of the body pointed away from the light. 

 In both instances the animals turned at once and went directly toward 



