1912] Morphology and Biology of Insect Galls 365 



A number of investigators have suggested that some form of enzyme 

 is secreted by the larvae of the Cynipidse. Kiistenmacher^^ indeed 

 states in this connection that he could detect a distinctive odor from 

 these larvae, but enzyme action has always been considered in relation 

 to the gall-producing stimulus and never with the feeding habits. The 

 gradual decrease in the proportion of sugar to that of starch, in the con- 

 tents of the cells, from the inside of the nutritive zone to the outside, 

 would seem to indicate a relation between the relative amount of sugar 

 and the proximity of the larva. Experiments were accordingly under- 

 taken with the purpose of deciding whether the larva was capable of 

 producing this change and of thus rendering the cell contents more 

 easily soluble. 



First Series of Experiments. 



Forty larvae of Amphiholips confluens Harris just removed from the 

 galls were placed in about 7 c.c. of starch solution made of corn meal. 

 The test tube containing the larvae was placed in a bath at 50° C, along 

 with a control. 



This starch was tested for sugar with Fehling's solution. No sugar 

 was found at the end of 2 hrs. but after 20 hrs. a test for sugar was readily 

 obtained. 



Second Series of Experiments. 



Forty-two larvae were placed in the same quantity of starch solution 

 and treated as in preceding case. 



No sugar was found at the end of 8 hrs. but after 12 hrs. from the 

 beginning of the experiment sugar was detected, and again at the end 

 of 24 hrs. 



Third Series of Experiments. 



Thirty-five larvae were placed in 7 c.c. of water and left for about 

 3 hrs. This water was then placed in an equal quantity of starch solution 

 and kept at about 50° C. as before. The water was tested before it was 

 poured into the starch and found to give an acid reaction. In this case 

 sugar was detected in 50 hrs. and a very decided reaction was obtained 

 after 70 hrs. The larvae that had been washed were placed in starch and 

 kept at 50° C. as before but sugar could not be detected. 



In all the cases cited above, as a control experiment, starch without 

 the larvae was kept in the bath under the same conditions as that which 

 contained the larvce. This starch did not give the slightest indication 

 of sugar at any time. From these experiments we conclude that 

 the Cynipid larvae must secrete an enzyme that has the property of 

 changing starch to sugar. It seems quite possible that other ferments 

 may be employed by the larva for similar purposes. To my knowledge 



