266 : The Rev. Parrıck KEITH on 
currence with the agency of gravitation, when the proper condi- 
tions of germination are present, regardless of all obstacles or 
inducements tending to divert it from its course, as being tlie 
natural direction of its proper aliment and support, except. in 
such cases as are exemplified in the germination of the misseltoe ; 
while it directs the plumelet uniformly upwards, and in opposi- 
tion to the agency of gravitation, when the above proper condi- 
tions are present, as being the natural direction of the medium 
that is the best suited to the developement of its parts. T 
If it is said that the attribute of vegetable instinct is still but 
an occult quality of an occult principle, of the abstract nature of 
which we know nothing, the objections we confess must be ad- 
mitted ; but the case is without remedy, as it is in the animal 
kingdom also, in which we know nothing of the nature even of 
the human mind itself, except from its operations. 
We do not, however, affect to exalt the living principle of the 
plant to the dignified rank either of a dryad or a sylph, the notion 
of whose fabled agency has been represented by Sir Humphry 
Davy as being equally credible with that of the philosopher 
who shall assume the agency of * any thing beyond common 
matter, any thing immaterial in the vegetable oeconomy*." And 
yet the agency of some such principle is so absolutely indispen- 
sable, that even while it is thus almost directly denied, it seems 
to me to be indirectly admitted ; unless I have altogether mis- 
apprehended the concessions which Sir Humphry makes on this 
subject. For although he thinks there are few philosophers who 
would be inclined to assert the agency of any thing beyond com- 
mon matter in the vegetable economy, yet he admits that vege- 
tables may be truly said to be living systems, in as much as they 
possess the means of converting the elements of common matter 
* Agricultural Chem. Lect. v. 
into 
