PSTCHE. 
The larva transforms in ten days and 
is, when fully grown, 44 mm. long. As 
it approaches maturity the four-cham- 
bered vessels [ovaries] become cylindri- 
eal, and twice their original length, and 
with points on the lower sides from the 
constricted parts. The fuller develop- 
ment of the alimentary canal and the 
longitudinal tubular fold [dorsal vessel] 
causes these smaller vessels [ovaries ] 
to recede more from the dorsal median 
line and approach nearer to the pleura 
in the comparatively free space occupied 
only by the. ramifications of the tra- 
cheae. Here they seem to be balanced 
upon and permeated by fine tracheae 
from the spiracle of the 9th segment, and 
move synchronously with the general 
impulse received through the series of 
spiracles on the pleura but begun in the 
pair on the 11th segment. This pair 
of spiracles, connected by a short trans- 
verse band or spiracular tube, gives rise 
to two sets of tracheae: one penetrating 
no farther than into the subcutaneous 
enveloping membrane, ramifies there, 
giving no, signs of activity; the other 
responds to, if it does not originate, 
every impulse of the larva. 
Each of the spiracles has a similar 
double set of tracheae acting in the 
same way. ‘The air tubes of the passive 
set just referred to, are inclined a little 
backward, transversely, at their free 
ends. while those of the active set, ram- 
ifying within the inner parts of the body, 
tend forward. A part of them, meeting 
on the middle of the venter, arch over a 
small, misty, suboval dot [nervous gan- 
glion} which has a faint sympathetic 
movement with the tracheae touching it. 
»~yy? 
323" 
One of these misty, white bodies is 
situated on each segment, beginning, 
from behind, at the 10th, where it seems 
to be a double, oval dot, and is presuma- 
bly composed of the ganglion of the 
11th and 10th. 
to this are single. 
The next four anterior 
The fifth and fourth 
are near each other and nearer the 3rd 
segment, showing a forward tendency. 
Each of the three thoracic segments has 
its separate ganglion, equidistant from 
each other, and nearer together than the 
series posterior to them. Each of these 
ganglionic nuclei is situated in the ante- 
rior angle of a triangle of white filaments 
whose base line is almost straight across 
the segment. 
On the dorsum and ending on the ven- 
ter are long tubes (malpighian vessels) 
one on each side, first traceable near the 
10th spiracle, with which they are con- 
nected by a bent tubular line. Follow- 
ing a direct course forward from this as 
far as the 6th, these tubes recurve and 
return to the 9th. going forward once 
more at an acute angle and losing them- 
selves in the 5th, but becoming again 
visible just below the third segment. 
These tubes are of the same size and ap- 
pearance as the tracheae, with which they 
come in frequent contact. At the pos- 
terior end of the third segment, are the 
blunt ends of a pair of tubes [silk ves- 
sels]. These faintly traced 
almost to their position on the head as 
the spinnerets. 
At times when the larva is undisturbed, 
there seems to be an almost total suspen- 
sion of motion in the spiracles and in all 
the parts affected by them. With the en- 
trance of air into the system of spiracles 
may be 
