No. 428.] THE METAMORPHOSIS OF SISYRA. 627 
Fig. 14 shows the effect of a greater stretching in a 
longitudinal direction. Most of the nuclei have returned to 
their position next the cuticle. A very few have progressed 
too far for return, and are left clinging to the tracheal open- 
ings or standing alone 
and apart from their 
fellows. The cell pro- 
cesses are much more 
ragged and broken 
than in the last stage, 
and the basement 
membrane is pulled 
out of its straight line, 
being very uneven and 
irregular. Traces of 
FiG. 15. — Pupal wing. c, rudimentary chitin; 4, mother the old connection 
cell of hair; 7, leucocytes ; z, trachea. 
may be seen, however, 
in the slight thickenings in the cell processes. Along the 
tracheal openings where the adult veins are to be, we see 
preparation going on for the task of depositing extra layers of 
chitin. At these points the cells become aggregated in two 
or more apparent layers and have larger nuclei. 
The next section figured is from the wing of a pupa 
(Fig. 15). Here the wing has increased greatly in length and 
decreased in thickness. The slender cell processes have 
almost entirely disappeared, all the cells are on one level and 
have secreted a thick 
layer of material, 
which, after the final 
molt, will harden 


into chitin. Owing P 
to the close quarters : 
within the pupal rre. epe E cs a, soon after molting ; 2, older. 
skin, the wing has trachea; A, cee cel of hair; 7, leucocytes. 
become extensively fluted and crinkled to permit the now rapid 
growth longitudinally. In Fig. 15 a hair cell is shown develop- 
ing in the cuticle, —a large vacuolated mother cell, with nucleus 
at one side and small cells clustered about it. 
