1^ Journal New York Entomological Society. [voi.viii. 



caterpillar spins up, the tracheae show very flilntly but as the age in- 

 creases they appear more prominent and the intima is very evident. 

 During the early part and the middle of the last larval stage the tra- 

 cheoles (Fig. 12, // ) are in great abundance, but in the prepupal 

 stage they have begun to decrease in number and extent (Fig. 22, // ). 

 As the caterpillar moults for the pupa the intima of the main trachea 

 (Fig. 16, ///) is pulled out which opens the mouths of the wing 

 trachere and allows air to enter ; and the trachea; thus become func- 

 tional. It is a question as to what now becomes of the tracheoles. 

 Gonin says' that they are drawn out at the time of this moult. He al- 

 so says that this can be easily demonstrated. But the results of my 

 observations are very different, as will appear later. 



The Pupal Wim(;s. (Plate III, Figs. 24 and 26. Plate IV, ex- 

 cept Fig. 29 and Plate V. ) 



During the pupal stage several important changes take place in the 

 structure of the wing : the temporary or larval tracheoles disappear ; a 

 secondary or pupal system of tracheoles arises : important changes 

 take place in the trachea; ; and a complicated series of changes takes 

 place in the form of the hypodermal cells and of the l)asement mem- 

 brane. 



The Disappearance of f/ie Temporary Tracheoles. — The temporary 

 tracheoles are found in pupal wings (Fig. 26, //) but not in such 

 great numbers as in larval wings. They run in straight lines much 

 the same as in the larval wings, but they are found oi)ly in the axial 

 region of the wing, and that only in very young pupa;. They are at- 

 tached to the epithelial wall of the trachea (Fig. 2)2,^ ^H- '^'his evi- 

 dence will add to the proof of the theory of Landois and Pancritius 

 who thought that the tracheoles of the larva disappeared by absorption 

 in the pupa, and disapproves the statement of Gonin referred to above. 



The Deve/opinenf of the Secondary or Pupal Tracheoles. — A new 

 system of tracheoles now arises from the trachea;. This may be 

 called the secondary system of tracheoles. The two systems are en- 

 tirely different and have no relation the one to the other. The tem- 

 porary or larval system has its origin from the main tracheal trunk or 

 from the bases of the Aving trachea, while the pupal system has its 

 origin from the trachea; in the wing itself and functions during the 

 pupal life. The secondary system extends at right angles to the 

 trachea; and ])enetrates the wing substance (Fig. 24, //) while the 



