12 
just before the egg is deposited by the female. After fecundation and 
before deposition the egg of some varieties is covered with a gummy 
varnish which closes the micropyle and serves to stick the egg to the 
object upon which it is laid. Other varieties, however, among which 
may be mentioned the Adrianople whites and the yellows from Nouka, 
in the Caucasus, have not this natural gum. As the hatching point 
approaches the egg becomes lighter in color, which is due to the fact 
that its fluid contents become concentrated, as it were, into the central 
forming worm, leaving an intervening space between it and the shell, 
which is semi-transparent. Just before hatching, the worm within be- 
coming more active, a slight clicking sound is frequently heard, which 
sound is, however, common to the eggs of many other insects. The 
shell becomes quite white after the worm has made its exit by gnawing 
a hole through it, which it does at the micropyle. Hach female pro- 
duces on an average from three to four hundred eggs. In the standard 
ounce of 25 grams* there are about 50,000 eggs of the small Japanese 
races, 37,500 of the ordinary yellow annual varieties, and from 30,000 
to 35,000 in the races with large cocoons. The specific gravity of the 
eggs is slightly greater than water, Haberlandt having placed it at 1.08. 
It has been noticed that the color of the albuminous fluid of the egg 
corresponds to that of the cocoon, so that when the fluid is white the 
cocoon produced is also white, and when yellow the cocoon again cor- 
responds. 
Toe LARVA OR WorRM.—The worm goes through from three to four 
—<—== 
Fic. 1.—Full erown larva or worm (after Riley). 
molts or sicknesses, the latter being the normal number. The periods 
between these different molts are called “ages,” there being five of these 
ages, the first extending from the time of hatching to the end of the 
first molt, and the last from the end of the fourth molt to the transfor- 
mation of the insect into a chrysalis. 
The time between each of these molts is usually divided as follows: 
The first period occupies from five to six days, the second but four or 
five, the third about five, the fourth from five to six, and the fifth from 
eight to ten. These periods are not exact, but simply proportionate. 
The time from the hatching to the spinning of the cocoons may, and does, 
vary all the way from twenty-five to forty days, depending upon the 
race of the worm, the quality of food, mode of feeding, temperature, 
4281 grams = 1 ounce avoirdupois. 
