[ 294 ] 
kind of vegetable is prejudicial to another; whereas 
much heat and moiflure together are equally indul- 
gent to all. This, in my opinion, fhews that each 
plant hath a fpecific vegetation of its own, as well 
as one common to all, and that the former depends 
upon fomewhat elfe than mere warmth and moift- 
ure. 
The conftitution therefore of the year difpofes 
the vegetative fpirit, whether refiding in the air, the 
earth, the water, or in all, to fupply fometimes 
thefe, and fometimes thofc vegetables, with a greater 
or lefs proportion of aliment. By thefe means a 
greater quantity of that juice, which diftinguifhes 
any one fpecies of plants from all others, and ena- 
bles it to give life and food to its peculiar inhabit- 
ant, mull neceffarily be produced one year, than 
another; and confequently the eggs, depoftted in 
the cavities, or perhaps in the very perfpiratory 
pores of its bark, muft be better cherifhed, and the 
worm more plentifully fed by the leaves, which in 
fuch a year contain a greater abundance of the fpe- 
cific juice, and that more perfe&ly elaborated. 
From hence it may feem reafonable to reft in 
this conje&ure, till fomewhat more certain is found 
out, that the annual conftitution being more in- 
dulgent to the vegetation of one plant than of an- 
other, promotes the growth and fertility of this, 
which is of a ftmilar, and checks the increafe of 
that which is of a diftimilar nature. The plants, 
thus differently fupplied, furnifh their refpe&ive in- 
fers accordingly. Hence again it comes to pals, 
that many fpecies of infers, having been injured 
by fome unknown difpofttion of the air or earth, 
feeni 
