THE REACTIONS OF NORMAL AND EYELESS 

 AMPHIBIAN LARVAE TO LIGHT 



HENRY LAURENS 



, Oshom Zoological Laboratory, Yale University 



TWO FIGURES 



A great deal has been written about the photic reactions of 

 amphibians, but this has been concerned chiefly with the adults, 

 the larval forms having received but scant notice. In the spring 

 of 1913 a series of experiments were carried out upon the larvae 

 of Rana pipiens, R. sylvatica, and Amblystoma punctatum to 

 determine whether they were sensitive to light, and if so, whether 

 they were sensitive to light received through the skin as well as 

 to light received through the eyes. 



I take this opportunity to express to Dr. R. G. Harrison my 

 thanks for suggesting this piece of work to me, as well as for his 

 continued interest a^d criticism. 



Banta and McAtee ('06, p. 71) have noted that the larvae of 

 the cave salamander are much more responsive to light than are 

 the adults, and that the younger larvae are more responsive than 

 the older. Both larvae and adults are negatively phototactic. 

 Eycleshymer ('08) found that Necturus larvae were negatively 

 phototactic, both in their natural environment and in the aqua- 

 rium; furthermore, that they orient in a definite way, such that 

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



The only other mention made of the reactions to light of am- 

 phibian larvae is that by Franz ('10 and '13). Franz describes 

 tadpoles as being indifferent to light — non-phototactic— except 

 when they are crowded into a small space, under which conditions 

 they will all orient themselves to the rays of light, so that their 

 heads are directed toward the source of light. Franz cites this 

 case as one of the numerous examples of so-called phototaxis, 



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