200 



HENRY LAURENS 



Although the results of the reactions of the individual larvae 

 were kept separate, they were throughout so similar that there 

 is no need to give them separately and they are given combined, 

 in table 1. Five groups of ten larvae each were tested for the 

 reactions of normal individuals, and four groups of ten each for 

 those of the eyeless. It is seen, by referring to the table that, 

 in the case of the normal larvae, out of a thousand reactions, 786 

 were positive, and 127 negative, while 54 were indifferent, and 

 33 gave no reactions within five minutes. In percentages these 

 results give 79 per cent positive, 13 per cent negative, and only 

 5 per cent indifferent, and 3 per cent no reactions within five 

 minutes, 



TA.BLE 1 



Photic reactions of normal and eyeless Amblystoma larvae 



The eyeless individuals are almost as decidedly positively pho- 

 totactic as the normal are. Here there are 71 per cent positive 

 and 15 per cent negative, a decrease of 8 per cent, compared with 

 the normal larvae, in positive responses and an increase of 2 

 per cent in the negative. There is, however, a larger percentage 

 of indifferent reactions and more of them do not react in five 

 minutes, than in the case of the normal larvae. 



These results show that the larvae of Amblystoma punctatum 

 are positively phototactic in response to stimulation received 

 through the skin as well as to stimulation received through 

 the eyes and the skin. These results are in accord with what 

 has been found by many investigators of the light reactions of 

 the amphibians, that is, that the eyes are not essential for the 

 light reactions, for the latter may be brought about by stimula- 

 tion through the skin. Parker ('03), Pearse ('10), and Laurens 

 ('11) have reviewed the literature of this subject, and there is 



