328 Conjiderations on oviparous 
rent, till the Embrio having attained a eer**. 
tain State of Maturity, endures Confinement 
no longer, burfts open the Integument, Cafe, 
or Shell that inclofed it, and ifiues there¬ 
with from the Body of the Parent : until 
which Time the Embrio receives its Nourifh- 
ment from the Blood and Juices of the Pa¬ 
rent, which are conveyed into the Body of 
the Embrio , by certain Vellels of the Parent 
that inofculate with correfpondent Veffels of 
the Embrio , and at the Birth become fepa- 
rated therefrom. 
Hence it appears probable, that the origi¬ 
nal Principle of Life, the gradual Expanfion 
and unfolding of the Members, and the 
Progrefiion towards Maturity and Birth, are 
nearly,. the fame, whether the Embrio be 
diatched within the Body or without the Bo¬ 
dy of its Parent ; which feems to be the 
' chief Difference between viviparous and ovi? 
parous Production. But to proceed. 
For fome Days after the Water Snail has 
laid its tranfparent Egg, the Microfcopic 
Speck of Life, wherein the tender Limbs and 
Rudiments of the Animal are mod wonder¬ 
fully folded up and contained, has no other 
Appearance of Life than only a languid 
Pulfation , but juft difcernible by the beft 
. Qlaffes and the moft curious Eye. As this 
Speck increafes in Bignefs, it exhibits, gra¬ 
dually, the Figure of a minute Snail, and 
acquires- an Ability of moving itfelf very 
fiowly. 
