76 INTERNAL ANATOMY OF INSECTS. 
nion—that the respiration is intimately connected with 
the conversion of the food?. In the zmago, there ap- 
pears to be more provision for storing up the air in vesi- 
cular reservoirs, than in the larva. Wonderful is the 
mode in which some of the changes in the internal struc- 
ture, which these variations indicate, must necessarily 
take place. They are, however, probably not more sin- 
‘gular than those which less obviously occur in the air- 
vessels of all insects in their great change out of the larva 
‘into the pupa state. But having before enlarged on this 
subject, I need not repeat my observations?. 
The access of air is as necessary to insects even in 
their egg state‘, and in many cases its presence seems 
provided for with equal care, by means as beautiful as 
those Messrs. Home and Davy have shown to occur in 
the oxygenation of the eggs and foetuses of vertebrate 
animals¢, It is only necessary to view the admirable 
net-work of air-vessels which Swammerdam discovered 
spread over the surface of the eggs of the hive-bee while 
in the ovaries*,—a provision which, from analogy, we 
may conclude obtains generally; from the importance 
which nature has attached to the oxygenation of the germ 
while in the matrix. And judging from analogy, we may 
infer that the access of this element is as carefully secured 
after the egg is laid, as before. The egos of most insects 
being of a porous texture, often attached to the leaves of 
* In Linn. Trans. iii. 302. > Vou. III. p. 196—. 
© Spallanzani found that the eggs of insects placed under the ex- 
hausted receiver of an air-pump, or in any small closed vessels, did 
not hatch, though every other condition for their developement was 
present. Opusc. de Phys. i. 141. 4 Philos, Trans. 1820. 213. 
© Bibl. Nat. i. 204. b. t. xix. fi 5. 
