RESPONSES OF LARVAE OF AMBYSTOMA 65 
ments, like the de-eyed larvae of Ambystoma tigrinum in the 
experiments described in this paper, responded not only to me- 
tallic rods but also to non-metallic bodies on which an appreci- 
able electrical current could not be generated by contact with 
water, these responses can not be the results of electrical stimu- 
lation. As suggested by Crozier, mechanical deformations in the 
water probably constitute the stimulus involved. The de-eyed 
hamlets used in Crozier’s experiments responded to the ap- 
proach of solid bodies at greater distances and more vigorously 
than the larvae of Ambystoma tigrinum used in the experiments 
described in this paper. Furthermore, the initial reaction in 
the characteristic responses of the former was negative, while 
that of the latter was positive in character. Doubtless this dif- 
ference is due to the fact that the receptors involved were stimu- 
lated more strongly in the hamlets than in the larvae of Amby- 
stoma. Obviously the form of sensitivity involved, which is epi- 
eritic in character, is less highly developed in Ambystoma tigrt- 
num than in fishes like Epinephelus striatus. 
The above experiments were carried out at the Iowa Lakeside 
Laboratory during the summer of 1920. The writers desire to 
express their indebtedness to Professor R. B. Wylie, Director, 
for the opportunity of working at the Laboratory and for his 
interest in furthering the work. 
BIBLIOGRAPHY 
Crozier, W. J.—On tactile responses of the de-eyed hamlet (EHpinephelus 
striatus)—Jour. Comp. Neur. 29: 163-175. 1918. 
Parker, G. H. and Van Hausen, A. P.—The responses of the catfish, Am- 
iwrus nebulosis, to metallic and non-metallic rods—Amer. Jour. Psychol. 
44: 405-420. 1917. 
