200 NEUROPTERA. 
Mot her » It avoids that by enveloping 
itself in a strong case, where it can se- 
cnrely undergo all its transformations : 
for this purpose it is provided with a 
store of fine silk, which, when first spun, 
is so sticky that small particles of sand 
adhere to it firmly. 
Lucy, I suppose, mamma, in the 
same way that some caterpillars glue little 
bits of wood to their case. 
Mother, The silky substance produced 
by different insects seems to be nearly 
of the same texture ; they derive it from 
a reservoir of a thick, glutinous fluid, 
which, in the formica leo, is placed near 
a minute aperture in the abdomen ; and 
as it is forced out through this opening, 
it acquires the form and tenacity of a 
very fine silk thread. 
By means of a small pointed organ, 
nicely adapted to the purpose, the thread, 
in spinning, is stuck to particles of sand, 
till the outside appears like a ball of sand 
kept together by a net work of white 
silk. 
