43 
nary summer weather. Their development may, however, be hastened 
or retarded by increasing or lowering the temperature. This fact is 
taken advantage of to obtain a few adult insects which may be micro- 
scopically examined before the whole lot becomes fully developed. 
I was very much pleased with the method employed by M. Maillot, 
which J had an opportunity of examining at Montpelier, in 1884, and I 
here give a description of it in his own words: 
“Three or four days before the cocoons are taken from the branches 
we take, here and there, from the early spinners as well as the late, 
several hundred cocoons; as, for example, five hundred from a lot of 90 
pounds. This sample should be placed in an oven or warm room, where 
it will be kept day and night at a temperature of from 100° to 110° Fah., 
and a high degree of humidity. In this way the formation of the moth 
is hastened. As during this time the cocoons of the lot itself remain at 
a temperature of from 75° to 90°, and often during the night at even 
lower temperatures, we shall still have time to stifle them if the lot is 
discarded, or to string them into chains if, on the contrary, it proves 
healthy. 
‘““Hvery two days we take ten chrysalides from the sample and ex- 
amine them microscopically for corpuscles. If we find them in the first 
eight or ten days, no matter in how small quantities, we can be sure 
that the proportion of pebrinous moths will be considerable. When the 
chrysalides are mature, which is easily seen by their eyes becoming 
black and the eggs harder to break under the pestie, and also by some 
of them turning into moths, we proceed to the definite examination, 
We crush one by one the moths which have come out and the chrysa- 
lides which remain and search for corpuscles; the per cent. which is 
thus found will not differ materially from that which exists in the whole 
lot.”* 
The examination of the chrysalides here mentioned may be made in 
the manner already described when searching for the ferment of flaccid- 
ity and at the same time. But if we are looking for the pébrine only 
we need simply crush the whole chrysalis in the manner hereafter de- 
scribed for the moth. 
Proceeding now with stock of which the purity has been ascertained 
by one or more of the different methods of observation above described, 
200 cocoons should be selected for each ounce of eggs that it is desired 
to produce. In making this selection great care should be exercised in 
taking only cocoons that are fine in texture and firmly made. This fine- 
ness is one of the prerequisites of a first-class cocoon. What is meant 
by this difference in texture will be seen by an examination of Figs. 2 
and 3, page 14, the former being fine and the latter coarse. The firm- 
ness of the cocoon, depending as it does on the amount of silk whieh it 
contains, is an indication of the vigor of the worm, and another item to 
be considered in selecting stock for reproduction. Rules hav e been 
*Maillot, Legons, etc., p. 250, 
