OF WASHINGTON, VOLUME XI, 1909 71 



as the insect is firmly braced, by means of its fore and middle 

 legs, the abdomen is forced into the ground.* 



Kunckel d' Herculais was fully aware of the wider bearing 

 of these observations and in addition to these upon Orthoptera 

 gives a number of less complete ones upon other insects. In 

 earlier investigations he had found that the ptilinum of cyclo- 

 rhaphous flies is not inflated by the pressure of air from the 

 tracheae but by blood forced into it from the general body 

 cavity by contraction of the thoracic and abdominal muscles. 

 Most likely in this case also the digestive tube is distended with 

 air when the imago issues from its puparium. Balbiani in- 

 formed Kunckel d' Herculais that a similar function is indicated 

 in the case of the homopter Conomelus limbata Fabr., for he 

 had found that its digestive tube is filled with bubbles of air at 

 the time of moulting. 



Hubbard in his observations on Psocus citricola Ashmead 

 describes the office of air in the hatching of this insect. f The 

 eggshell is perfectly transparent, so that the insect within can 

 be readily observed. Before hatching the young insect swal- 

 lows bubbles of air until the steadily expanding head finally 

 bursts open the egg. This observation was repeated independ- 

 ently upon an European psocid (Stenopsocus crnciatus L. ) 

 and described more in detail by Peyerimhoff.J He found 

 upon the amnion of the young psocid a frontal chitinous organ 

 consisting of a dentate ridge. While this structure is the instru- 

 ment for rupturing the egg-shell the ingested air furnishes the 

 necessary force. After the insect has hatched the amnion is in 

 its turn ruptured and shed by the pressure exerted through the 

 air taken into the digestive tract. 



Busck has observed that the larva of the tineid moth Mar- 

 mara salictella Clemens in its penultimate moult comes forth 

 greatly inflated and afterwards shrinks to its normal size. He 

 has recorded the curious use of the air in its digestive tract 

 made by the larva of this moth when forming its cocoon. 

 Globules are expelled from the anus, which consist of an aggre- 

 gation of small bubbles of air surrounded by some delicate 

 substance. The larva thrusts its anus through openings in the 



*Mecanisme physiologique de la punk- chez les Insectes Orthopteres 

 de la famille des Acridides. Role de 1'air comme agent mecanique et 

 fonctions multiple de 1'armure genitale. Compt. rend. Acad. Sci. 

 Paris, v. 119, pp. 244-247 (1894). 



flnsects affecting the orange, 1885, p. 195. 



$Le mecanisme de 1'eeosion die/ les psnques. Ann. Soc. Ent. France, 

 v. 70 (1901), pp. 149-152. 



Proc. Ent. Soc. Wash., v. 5, pp. 102-103 (1902). 



