FUNCTION OF THE (ENOCYTES OF INSECTS. 21J 



were taken out and it was found that the liquid in the test tube 

 containing the live enzyme had turned red. The fat-splitting 

 enzyme (lipase) had split the ethyl butyrate into alcohol and 

 butyric acid. The control test retained its former blue tint, 

 namely, that of the lacmoid. 



The next thing was to see with how small a quantity of ex- 

 tract and reagents the reaction could be obtained. For this 

 purpose very small glass tubes of equal sizes were blown. For 

 the liquids eye droppers of equal sizes were used. A drop was 

 sucked into the dropper and the glass was graded into four equal 

 parts, so that it was possible by having droppers of exactly the 

 same size and gradation to use for each test the same amounts of 

 liquid. The amounts of the substances were then decreased until 

 two drops of pancreatic extract and one fourth of the amount of 

 one drop of ethyl butyrate plus the lacmoid solution were used. 

 The toluol was never omitted. Control tests were again made 

 each time. The characteristic red color was obtained. 



When I was thoroughly satisfied that I had mastered the 

 reaction, I made an extract from the cenocytes of large leopard 

 moth larvae. Two caterpillars, each measuring about i^ inches, 

 were used for each experiment. All of the cenocytes were dis- 

 sected out in physiological salt solution and rubbed in a very 

 small agate mortar. The extract from the cenocytes plus a 

 small quantity of saline solution which was added equalled two 

 drops. This was taken without any further dilution and, accom- 

 panied by control tests, treated in exactly the same way as the 

 small amounts of pancreatic extract had been treated. Six 

 experiments were performed. In not one case did I get an acid 

 reaction. This seems to indicate that lipase or a fat-splitting 

 enzyme is not present in the cenocytes. 



It occurred to me that perhaps the fat of insects might be 

 different from vertebrate fat, and that after all the cenocytes 

 might secrete a ferment of some sort, the presence of which the 

 above reagents would not reveal and which might have the 

 power of splitting this fat. I could find in the literature on fats, 

 nothing but the broad statement that all animal fats are tri- 

 glycerides of oleic, stearic and palmitic acids. The important 

 question for me was therefore to determine whether or not insect 



