INTRODUCTION. 
XV 
young larva and infant plant, by heat and moiflure, 
rife into exiftence, increafe, and in due time arrive 
to a date of perfedt maturity ? The phyfiologifls 
agree in opinion, that the work of generation in 
viviparous animals, is exadlly fimilar, only more 
fecret and enveloped. The mode of operation that 
nature purfues in the production of vegetables, and 
oviparous animals, is infinitely more uniform and 
manifefl, than that which is or can be difcovered to 
take place in viviparous animals. 
The moil apparent difference between animals 
and vegetables is, that animals have the powers of 
found, and are locomotive, whereas vegetables are 
not able to fhift themfelves from the places where 
nature has planted them : yet vegetables have the 
power of moving and exercifing their members, and 
have the means of tranfplanting or colonifing their 
tribes almoil over the furface of the whole earth ; 
fome feeds, for inftance, grapes, nuts, fmilax, peas, 
and others, whofe pulp or kernel is food for ani- 
mals, will remain feveral days without being in- 
jured in flomachs of pigeons and other birds of 
paffage ; by this means fuch forts are diftributed 
from place to place, even acrofs feas ; indeed fome 
feeds require this preparation by the digeflive heat 
of the flomach of animals, to diffolve and detach 
the oily, vifcid pulp, or to foften the hard Ihells, 
Small feeds are fometimes furnifhed with rays of 
hair or down ; and others with thin light membranes 
attached to them, which ferve the purpole of wings ? 
on which they mount upward, leaving the earth, 
float in the air, and are carried away by the fwift 
winds to very remote regions before they fettle on 
the earth; fome are furnifhed with hooks, which 
catch hold of the wool and hair of animals paffing 
|>y them, and are by that means fpread abroad; 
b 4 other 
