ree 
RESPONSES OF LARVAE OF AMBYSTOMA 63 
made under favorable conditions the larvae responded to the 
near approach of the glass rod, or other solid bodies, in the char- 
acteristic manner. In the course of a week four of these larvae 
entered the final phase of their metamorphosis. As they be- 
came less active and sought to leave the water they no longer 
responded to the near approach of solid bodies. The remain- 
ing de-eyed larva was kept under observation in the laboratory 
for a period of three weeks. It did not fail to respond in the 
characteristic manner to the near approach of the glass rod or 
other solid objects, whenever the tests were made in the absence 
of conflicting stimuli. Other larvae, taken from another pond 
and de-eyed later, responded in the same manner to the near 
approach of solid objects one hour after the eyes were removed 
as well as on successive days following the operation. All at- 
tempts to elicit responses of the same type from young adults 
and larvae which were passing through the final phase of their 
metamorphosis resulted negatively. 
When a solid body approaches the head of a normal seeing 
larva in the water the reaction which takes place, doubtless, is 
mediated through the sense of sight. If the animal is hungry 
it may attempt to seize an approaching glass rod as it would a 
bit of fcod. On the other hand, if no feeding reaction is elicited 
the response which takes place is usually an effort to avoid con- 
tact with the object. Doubtless the normal seeing larvae have 
the same capacity to detect the presence of solid bodies in close 
proximity with their skin by some sense other than sight as the 
de-eyed larvae, but stimuli received through the eyes result in 
motor responses more promptly than those received from near- 
by solid bodies by receptors in the integument. 
Larvae with only one eye removed responded essentially in the 
same manner as the de-eyed larvae when a solid body approached 
the head from the eyeless side in such a manner that its pres- 
ence could not be detected by the intact eye. No response was 
elicited from these larvae by the near approach of a solid body 
to the lateral surfaces of the trunk, or any part of the body ex- 
cept the head. 
A comparison of the responses of the de-eyed larvae of Am- 
bystoma tigrinum, described above, with the responses of certain 
blinded fishes to the near approach of solid bodies in the water, 
