62 STATES OF INSECTS. (Lge. 
envelope of the human feetus, they therefore still continue 
a kind of foetus, so to speak, more or less enveloped 
under other tunics, and principally in their amnios, or 
the covering in which the foetus floats in the /iquor amniz*. 
This the butterfly does in the pupa-case ; and its birth 
from this, under this view, will be the true birth of the 
animal. In the human subject, the ova upon impreg- 
nation are said to pass from the ovary through the Fal- 
lopian tube into the uterus. In the insect world, upon 
impregnation, the eggs pass first from the ovaries into 
the oviduct, answering to the Fallopian tube, which in 
them terminates in the oviposztor, or the instrument by 
which the parent animal conveys the eggs to their pro- 
per station: there is, therefore, nothing properly analo- 
gous to the uterus in the insect, and the substance upon 
which the larva feeds upon exclusion answers the pur- 
pose of a placenta. 
After this general view of the most modern theories 
with regard to the metamorphosis of insects, I shall in the 
present and some following letters, treat separately of 
the different states through which these little beings suc- 
cessively pass. 
The first of these is the Ege state, the whole class of 
insects being strictly oviparous. Some few tribes indeed 
bring into the world living young ones, and have on that 
account been considered as viviparous, but incorrectly, 
for the embryos of none of these are nourished, as in the 
true viviparous animals, within a uterus by means of a 
placenta, but receive their development within true eggs 
which are hatched in the body of the mother. This is 
aN. Dict, d’ Hist. Nat. xx. 352. 
