VEGETABLE STRUCTURE. 
129 
tJiere be, or be not, a Circulation of the Juices in Plants. The analogy 
which obtains, in many infiances, between Animals and Vegetables, led 
many to think there was a general Circulation in the one as well the other ; 
and fome circumftances feemed to favour it. The opinion was received ; 
tho’ rather from probability than experiment or proof: and it kept its 
ground many years. Dr. Hales overthrew what thofe Writers had ad- 
vanced, by an accurate refearch, and a more certain philofophy : and at 
this time it is the received fyfiem, that the Juices of Plants do not circu- 
late ; but that an evaporation, and abforption, during the alternate changes 
of day and night, anfwer the purpofe. 
To determine that there is no circulation in Plants, becaufe we are able 
to overthrow the reafonings on which certain Authors eftablifhed their opi- 
nions that there was one, is rafli : for the fad may be fo, tho’ thefe have 
failed in the fupport of it. On the other hand, to queftion fads fo ab- 
foliite as thofe advanced by Dr. Hales, were raofl abfurd. The queflion 
has not yet been rightly hated : nor is it neceflary that one of thefe two 
fyhems fhould overthrow the other. There may be a returning courfe of 
the Juices in a Plant ; tho’ not univerfal, nor like the Circulation in Ani- 
mals : and this may be fo far from oppofing or diflurbing the fyhem of 
Evaporation and Abforption, that it may confpire and coincide with it in 
the ceconomy of the Plant. Reafon cannot deny that this may be ; and I 
perfuade myfelf experiments will fhew it is. This is the fyftem I would 
propofe to the world ; and I flatter myfelf they will receive it, fo far as 
evident fads, and plain experiment, fupport it. 
There can be no wonder that this was not found before; for by fome 
hrange fatality the parts wherein it is tranfaded, have been in a manner 
•unknown : the Flefli of Plants having been very imperfedly underftood ; and 
thofe conic Clufters of VefTels, fo elTential to the being of the Plant, not 
having been difcovered. The ufeful method will be, to trace the Juices 
and their courfe, along the Vefl'cls of thefe parts, in Plants of various 
kinds, beginning with thofe of the leafl; complex flrudure, and advanc- 
ing to the reft by gradual ftages. 
It is. the courfe of Nature that in the Seed is lodged a piece of the Flefli 
of the parent Plant ; and that when this is fown, and takes its growth, the 
termination of the w'hole is in new Seeds, in which are lodged alfo fuch 
pieces of the Flefh in the fame manner. We are therefore to trace the 
continuation of this Fleth, and confequently the courfe of its Juices from 
the body of the Root, which is the firft growth of the Seed, to the 
VoL. I. S Flower ; 
