29 



that it may almost be noted as the rule rather than the exception in 

 many large sections, as in emergence of Lepidoptera from the pupa. 

 Another object is to produce tension of a flaccid skin in order to 

 give a satisfactory fulcrum for muscular action, as in some young 

 larvae, in Psychid moths that lay their eggs very rapidly, in male 

 Psychids. 



A third use of inflation is to produce tension in the blood-spaces 

 to assist the expansion of wings and their appendages on emergence 

 from the pupa. In Lepidoptera this is the rule, and is a continuance 

 of the inflation that assisted emergence from the pupa. I have 

 made no observations on Hymenoptera or Coleoptera, and do not 

 know whether it occurs in these orders, in which it is unnecessary for 

 pupal emergence. 



I have nothing to tell you as to what the secreted gas is. It is 

 most simple to call it air. Until some one collects and analyses a 

 specimen we can only suppose that it is not air, but such a mixture 

 of oxygen, nitrogen, and carbonic acid as would be afforded by extract- 

 ing the gases dissolved in the blood of the insect, probably slightly 

 but not greatly modified by having to be secreted. It would be very 

 unlikely to be identical with air, and it would be equally impossible 

 for it to be chiefly carbonic acid. 



