436 



STATE BOARD OF AGRICULTURE. 



Jcill insects, there was no visible effect on the tissue pulp which might 

 be held as a sufficient cause for rapid death. 



As already pointed out, however, a rise in the respiratory ratio during 

 the time insects were dying, afforded the strongest evidence of an inhibi- 

 tion of oxygen assimilation. It was decided, therefore, to determine the 

 respiratory exchange of fresh insect tissue pulp and to see whether this 

 exchange became influenced by gasoline, for example, in the same man- 

 ner as had already been found for insects themselves. That the pulp 

 does have a decided respiratory exchange, and that this is influenced by 

 gasoline vapor in the same manner as the latter influences the respira- 

 tion of insects may be seen by comparing table I-A with table V of 

 part I, Tech. Bull. No. 11. 



TABLE I. 

 A. 



Gasoline was selected for making this test because of all the volatile 

 insecticides employed, it permitted of the most accurate volumetric de- 

 terminations of its own vapor, and of the oxygen, carbon dioxide and 

 nitrogen present at the beginning and at the end of the test. The ap- 

 paratus and the method employed for making the gas determinations has 

 been described in Part I of the former bulletin. The insect-tissue pulp 

 was contained in a small, sterile, open glass stender dish which floated 

 on the mercury in the respiration container. The pulp, or crude tissue- 



