Entomology, 933 
_ last moult. According to Adolph, these tracheal filaments rep- 
_ tesent the foundation of the vein-system,—to wit, of the concave 
_ veins; since the course of these, in the rudimentary wing, co- 
_ incides completely with the net-work of concave veins in the 
_ developed wing. Only later is every trachea shut in and closed 
_ time,according to Adolph, the trachez force the two wing-plates 
apart and beget a thinning of the wing-skin, which shows itself, 
among other ways, by the fact that the wings, in case of pressure 
these primary or concave veins appear later thickenings of the 
_ Wing-skin, in the form of chitine lines, with which, finally, trachee 
and blood-vessels associate themselves, and which form second- 
rt i 
‘ ‘Caused by thinning and the latter by thickening of the wing-skin ; 
and since in the former the trachea, in the latter the chitine-band, 
g only a na 
hy itse 
ight is j 
tein descending, like a parachute. This can be obse 
z 
__ by chitine-mass, and thereby transformed into a rib. At the same ` 
or draught, regularly tear along the concave veins. Between ` 
\ 
r 
; which still show approximately the fan type of vo s a : 
