STATES OF INSECTS. (Hge.) 87 
tect the included fluids from too rapid an evaporation, if 
the eggs be exposed to the full action of the atmosphere. 
In most Lepidoptera, and several other tribes, this inte- 
gument is considerably stronger, in those moths whose 
egos are exposed throughout the winter, as Zrichoda 
Neustria, &c., so hard as not to yield easily to the knife. 
Even in these, however, its substance is more analogous 
to horn or a stiff membrane than to the shell of the eggs 
of birds. Nothing calcareous enters into its composition, 
and it is not perceptibly acted upon by diluted sulphuric 
acid. The eggs of birds are lined by a fine membrane ; 
but I have examined several of those of insects, and 
have been able to discover nothing of the kind in them. 
I will not, however, affirm that it does not exist, though 
the shell of the insect egg appears more analogous to the 
membrane that lines that of the bird than to the outside 
shell itself. 
Within this integument is included a fluid, on the 
precise nature of which, except that it is an aqueous 
whitish fluid, few or no observations have been made, or 
indeed are practicable; but it is reasonable to suppose, 
that like the white and yolk of the bird’s egg, it serves 
for the development of the organs of the germe of the 
future insect. 
But few observations are recorded that relate to the 
embryo included in the egg. It is stated, that it is in- 
vested with an extremely fine and delicate pellicle—sup- 
posed by some analogous to the Chorion and Amnios of 
the human foetus, though others think the shell of the 
egg to correspond with the Chorion, and the successive 
integuments of the larva with the Amnios?. When the 
* Compare N. Dict. d’Hist. Nat. xvi. 246. with xx, 352—; but as 
