OF WASHINGTON, VOLUME XI, 19Q9. 69 



hotel called my attention to "a very strange animal." Upon the 

 veranda floor was a large cockroach (Periplaneta ainericana) , 

 which had just moulted and was resting with its hind feet still 

 upon the cast skin. Its glistening white color made the over- 

 familiar insect appear strange to the attendant. 1 placed my 

 foot upon the insect, whereupon it burst with a loud report 

 which could be heard all over the building. 



It seemed evident to me that this inflated condition at the 

 time of ecdysis, found in such widely different insects, could 

 not be exceptional. More probably it is not only general among 

 insects, but even an essential factor in the moulting process. 

 Naturally I turned to entomological literature in the expectation 

 of finding some explanation of this phenomenon. However, 

 upon examining a number of the best treatises on entomology, 

 I found, much to my surprise, that not one of them alluded to 

 the function of air in ecdysis. Nevertheless it had been ob- 

 served and studied and I finally came upon a series of papers 

 which deal with this subject or touch upon it. 



The earliest of these papers is by Jousset de Bellesme and 

 records observations upon the last moult of a dragon-fly.* He 

 found that the dragon-fly upon emerging from the nymphal 

 skin at once increased to about twice its previous size. This 

 was accomplished by air pressure within, for, when the insect 

 was punctured, it immediately collapsed. More careful inves- 

 tigation showed that at this time the main tracheae were not 

 filled with air, but the digestive tract was inflated with air. 

 As there is a fixed quantity of blood within the body this 

 blood is driven to the periphery by the pressure exerted by the 

 greatly dilated digestive tube. Jousset de Bellesme also as- 

 cribes the development of the imaginal colors and the hardening 

 of the chitin to the abundant blood-supply thus forced to the 

 periphery. In summing up he makes as his main point that 

 the dragon-fly, by employing air to inflate its digestive tube, 

 obtains the necessary force to accomplish the greater part of 

 its transformation. Thus during ecdysis the digestive tract 

 assumes a function entirely distinct from that of normal life. 

 In concluding he remarks: "Everything leads one to believe 

 that what I have described in the dragon-fly is repeated in a 

 large number of insects and constitutes a very general mechan- 

 ism in this class of animals." 



After a considerable interval Kunckel d' Herculais pub- 

 lished his observations upon the ecdysis of certain Orthoptera 



*Phenomenes qui accompagnent la metamorphose chez la Libellule 

 deprimee. Compt. rend. Acad. Sci. Paris, v. 85, pp. 448-450 (1877). 



