and Animalcules adhering to them, 327 
of this little Creature, fome reafonable Con¬ 
jecture may be formed of wbat happens in 
thofe of much larger Kinds. 
According to the ufual Order of Nature, 
every Embrio of an Animal is lodged for a 
Time within the Uterus of the Parent, in- 
clofed in a Cafe or Egg, whofe outer Coat is 
either hard and fhelly, or tough and mem¬ 
branaceous, affording a proper Bed and Co¬ 
vering to preferve it from external Injury. 
In Animals that are oviparous , this Egg 
is excluded out of the Body of the Parent, 
fome conliderable Time before the Embrio 
has attained a Size and Strength fufficient to 
endure being expofed to the open Air with¬ 
out Prejudice : during which Time, it takes 
in Nourifhment, and its Limbs acquire a 
continual Growth, from proper Juices in 
which it floats, and wherewith the Egg is 
replete. For the Egg, between the Time of 
its being laid, and that of its hatching, can 
receive no other Benefit from the Parent, 
than what the natural Heat of her Body can 
afford it; And Experience teaches that the 
like Degree of Heat, fupplied by any other 
Means, with the fame Conflancy, will be of 
equal Service •*. 
On the contrary, in viviparous Animals, 
the Egg is retained in the Uterus of the Pa- 
* In the Eggs of nunjberlefs Species, which fhew 09 
Concern for them after they are once laid, no more Heat at 
ail is neceflary, than what is common to the $ir or Water 
W which they are expofed. 
Y 4- rent. 
