RESPONSES OF THE DE-EYED LARVAE OF 
AMBYSTOMA TIGRINUM (GREEN) | 
TO SOLID BODIES 
By ALBert Kuntz and Jos& ZozAya 
St. Louis University School of Medicine 
While studying the feeding reactions of de-eyed larvae of Am- 
bystoma tigrinum, a characteristic reaction was observed when 
the forceps were brought near the head in the water when no 
food was present. As the forceps approached from the side 
the animal would turn its head in that direction. It would then 
resume a position of rest or move slowly backward or forward. 
Sometimes it would attempt to seize the forceps as soon as their 
presence was detected. 
In the further study of these responses the forceps which were 
used for handling food were discarded and a clean glass rod 
and other clean objects were used. A number of larvae 
which had been de-eyed three days previously, were placed in a 
shallow circular aquarium either singly or in groups of two or 
three and allowed to remain undisturbed until they 
became relatively quiet before observations were begun. As the 
glass rod was slowly and carefully brought near the head from 
either side the animal responded by turning its head toward the 
rod when it was still 5 mm. or farther distant. Sometimes the 
reaction occurred when the rod was still 20 mm., or farther, 
from the head. When the rod approached from above, the head 
was elevated; when it approached from below, the head was de- 
pressed. The reaction was essentially the same whether the rod 
approached the head at the level of the base of the gills or nearer 
the anterior end. In some instances the movement of the head 
toward the rod was the only response elicited ; in other instances, 
after turning the head toward the rod, the animal would swim 
slowly backward or forward. Occasionally it would attempt to 
seize the rod as soon as the head was turned toward it. All 
the larvae used in the initial experiments responded to the near 
Contributions from the Iowa Lakeside Laboratory, No. 54 
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