The vegetable SYSTEM. 
S 
all Vegetables. The Plants which grow in fun -burnt defarts and 
parched fands are no objection ; for they are fupplied from the air, 
as Sea-plants from the water ; imbibing nouriihment at their whole 
furface. 
As the Earth wherein Plants grow is more or lefs foluble in water, 
they flouridi more or lefs ; and there is fome difference alfo in the 
flate of it. Pure black mould is of all Earths the mofl foluble, there- 
fore Plants grow largefl; in this. The mould of garden-borders is 
an inflance : and in wild nature the Burdock, Thiflles, and Hem- 
lock fhew themfelves upon this Soil in all their lofty ftature : on 
the contrary, Clay, which diffolves more difficultly, affords the low 
Knotgrafs, Swines-crefs, and fome of the hardier Trefoils. Chalk 
offers certain fpecies fomewhat larger, as it is fomething more diffo- 
luble ; the Kidney-vetch, the Refeda, and the Campanulas, Sand 
has its place in the enquiries of an excellent guide, Linnaeus, on 
this head ; but certainly without juft reafon. Sand is a debafed 
Cryftal : this cannot be broke or diffolved at all by the water ; it 
is not Earth, nor can it nourifh Plants. Thofe which are found 
on fandy foils are fed only by the loofe Earth wdiich happens to be 
among the Sand : thererefore they are lefs conftant in their nature. 
Where fands are very poor, vve fee the low Plants, Rupture-wort 
and ftarved Serpyllum ; when there is more Earth among them w^e 
fee Grades or Reeds, or fhrubby Heath or the tall Fox-glove. 
There is no certain character of the Plants of fandy Sods, becaufe 
they depend upon the kind and. quantity of real Earth which is 
among the Sand.. 
Earth of a left proper kind may feed Plants luxuriantly w’hen 
art or accident have rendered it more foluble in water : it is hence 
that the field-culture makes Ver^etables larr^e : and hence ditch - 
banks of Clay, after they have been railed a time, feed the tall Na- 
vew : what the implements of hufbandry effedt in the firft cafe the 
air does in the other; breaking and mellownng the foil, and render- 
ing it eafier to be difiblved by water. It is thus manures adt alfo : 
they raife a fermentation which divides the Earth ; and it becomes 
fit for giving nouriftiment to Plants for many of thofe ingredients 
which effetft this change in Earth will not feed plants alone : fait, 
VoL. IL C fea- 
