The vegetable SYSTEM. 
7 
exhales it all day long, and the Plant fades under his influence only 
for that reafon : but the evening-dews reflore it. 
Plants fet in mould of ever fo rich a kind, if it be abfolutelv 
dry, receive no nourifliment ; but fade inftantly and irrecoverably. 
On the other hand, any Plant fet in Water, and covered to keep in 
the Moifture it exhales, will live and grow. We think fome Plants 
will live in water, and others not : but all will do it if the moill: 
vapour they exhale be returned upon them. Thofe which live in 
the open air with their Stems plunged in Water perfpire lefs, and 
therefore a lefs fupply wdll preferve them j thofe which evaporate 
more require to be fupplied alfo from their Leaves imbibing a moifl: 
Atmofphere. This is all the difference. 
On Water thus evaporated, and thus received, depends in a great mea- 
fure the peculiarity of certain Plants being found in climates ; and the 
Angularity obferved before, that though different countries, under vari- 
ous climates, produce diftindf Plants, thofe in the fame latitudes are not 
always the fame. Not only a certain warmth in the air, but an 
appropriated conflruftion of the parts of evaporation is requifite for 
this purpofe. Plants whofe leaves have the fame or a like texture 
are found in different countries under equal latitudes ; but thofe 
which are particular in this refpedV, perfpiring, whether it be lefs 
or more than the ulual proportion, can be found only in thofe places, 
under an equal heat, which, from the degree of Moifture in the air, 
afford a proportioned fupply. 
Thus Water is eminently concerned in that peculiarity of Plants 
and places, the caufe of which mufl; have been fought in vain, while 
the whole was attributed to heat. A proof of this is evident in thofe 
fpecies which live under Water; for there evaporation and abforption 
being fmall and Ample, and the degree of heat tempered extreamly 
by the depth, the fame fpecies are found in the moft diAant cli- 
mates : thus the common yellow Water-lilly and the Lentibularia, 
w'ith fevcral other English Plants, which grow under deep Waters, 
are found in China and the Indies ; thjugh they have alfo others 
of the fame fpecies which are not known here. 
To 
