42 
“ Cut away the walls of the thorax of the chrysalis with fine SCISSOFS, 
after the manner shown in Fig. 24, so as to reveal the stomach s. Draw 
this out with a pair of tweezers. The re- 
stricted part of the digestive tube, whic’. 
unites the stomach with the urinal sack 
u, Should then be cut. The anterior part 
of the digestive tube now alone holds the 
stomach in place, and this easily gives 
way. Lay the small ball thus withdrawn 
on a glass slide and scratch away the 
very soft, fatty envelope which covers the 
Fi¢.24.—Anatomy of thechrysalis, show. J4terior. Of this interior substance take 
eee Lea ges the stomach a, piece as big as the head of a pin, wash 
it with a drop of distilled water, and, 
placing it upon a slide with a cover glass over it, examine it with a 
microscope magnifying about four hundred diameters. With a little ex- 
perience this work may be done very rapidly. It would be well to take 
out at the same time the stomachs of, say, twenty chrysalides, and lay 
them on as many glass slides. * * * 
‘The first few days after the formation of the chrysalis the contents 
of the stomach are generally very liquid, which makes their extraction 
inconvenient. It is better to make these observations seven or eight 
days after the spinning begins, when the matter will be found to have 
more consistence. * * * Fig. 23, page 38, shows the appearance of 
the ferment found in flaccid chrysalides under a magnifying power of 
400 diameters. It is associated with the débris of leaves, morsels of the 
trachea, and chlorophyl cells. These matters ordinarily accompany the 
little ferment in the stomach of the chrysalis, because of the incomplete 
digestion of the leaf whenever it is submitted to fermentation.” * 
No parasite indicative of flaccidity has been discovered other than 
this ferment, which is not found in the adult insect; and if the trans- 
formation into the moth is permitted, all opportunity will be lost for 
detecting the disease. 
In pébrine, on the contrary, the corpuscle is found in the moth as 
well as in the chrysalis. We might, therefore, wait for a final exami- 
nation of the moth to be made after oviposition. But, in case disease 
is then found, it will be too late to stifle the cocoons, and the emergence 
of the moths will have ruined them for certain commercial purposes. 
For this reason it is important to detect the disease, if it exists, at as 
early a stage of the work as possible. If the larve have shown no ex- 
ternal signs of the pébrine, it would be well to microscopically examine 
a few of the last worms to spin. The corpuscles will be found in these 
laggards, if anywhere. 
Isolation and examination of the moths.—If left to themselves the in- 
sects remain in the chrysalis state for from two to three weeks in our ordi- 
“Pasteur, Etudes, ete., Vol. I, p. 233. 
