cS-i Bulletin eie la Suciélé tiitomologique d'Egypte 



Yiues ol' Ilio wings coiisisl ol' liachcae lyinj^ in a hollü^v 

 cavily, llic perilrachi'al space being silnaled chicHv 

 under and on each side of Ihe trachea " (1 ). 



The cross veins are dislingnished l'roni llie foregoing 

 1)V Ihe absence ol' Iracheae and serve only as passages 

 lor the i)l()0(l. Directly connected with the jieiitrachea' 

 sheatlis the cross channels nuisl be considered as similar 

 structures in wliich the trachea is atrojihied. The blood 

 corpuscles enclosed within the sheaths appear, on stain- 

 ing, as small oval or rounded luicleated cells. 



Widely scattered in tlie central portion of the wing, 

 these cori)Uscles congregate in large num])ers in the 

 peripheral region. 



An interesting tact is that some ol the cross channels 

 are discontinuous. The vein, suddenly interrupted, 

 opens among the cells of the interstitial tissue. This 

 rather peculiar arrangement is probai)ly connected with 

 the extravasation already mentioned. 



A h'w moi-e details can be added l)y an examination 

 of the sections; (Fig. 10). V\vs[, the interstitial tissue 

 appears to l)e divided into two layers, one dorsal, the 

 other ventral. The dorsal layer is essentially composed 

 of cuneiform cells of which the basal |)ortion (which 

 contains the nucleus) adheres to the cuticle while the 

 tapering portion projects into the interior where it 

 usually meets with some prolongation of the other layer. 

 The ventral layer is coiiiposed of flatter cells, ramilied 

 so as to form a kind of network. 



1. A dcvcl()i)ing wing sliowing, in the nciglil)ourliO()(t 

 of eacli vein, ttie traeiien -.xnd c<)rrcs|)oiicling pcrilrachc;d 

 ciivily lias Ijcen drawn h\ (ioxix (1S!)I; in iiis work on Ihe 

 nietaaiorphosis oi Pievis In-assicae. 



