224 THE INSECT WORLD. 
the silk-producing organ is continued in an enlarged portion D E, 
which is the reservoir of the silky matter. To the extremity, H, 
of this reservoir, is attached another capillary tube, E F’. These two 
capillary tubes, proceeding from the two glands, 
unite together like two veinous trunks, as the 
plate shows, in one single, short canal, F, which 
opens in the mouth of the worm, at its under-lip. 
It is in the narrow hinder tubes that the silky 
matter is formed. It collects in the swollen part 
D £, which is, properly speaking, the reservoir ; 
and remains there in the glutinous state. Having 
reached the capillary tubes, it begins to assume 
consistency, and forms two threads, which are 
united together at the point of junction of the 
tubes, and come out through the orifice, with the 
appearance of a single thread, to be conducted and 
directed by the animal to those points it has. 
selected. | 
It was hoped that by taking from the body of 
the worm the viscous matter contained in the 
Sa glands, silk could be formed. But this hope was 
Ve tl emo disappointed. It was found possible, it is true, 
7 to take the silk out; to draw it out into threads 
more or less fine; but up to this time it has only been possible in 
this way to obtain a matter which, when dried, more or less resem- 
bles catgut, and is easily enough spoilt by water. 
The viscous substance contained in the glands must then be 
elaborated by the insect itself. When it arrives in the conduit 
common to the capillary tubes, under the form of a thread, it is 
impregnated with a sort of varnish, which is poured into them 
from two neighbouring glands. The varnish unites the two 
threads into one single thread, and imparts to it the brilliancy of 
silk, and the property of resisting the action of water. It is 
during the last phases of the worm’s development that the silky 
matter becomes abundant in the glands. At this period, the 
animal eats much; and it is certain that the substance to be con-™ 
verted is furnished by the leaf of the tree on which the insect 
feeds. 







