264 The Rev. Mr. Keith on Germination.  [Aprit, 
well known to do. For then it would have no choice but to 
descend, unless prevented by an obstacle that could not be sur- 
mounted ; which might stop it or turn it to the one side, but 
could not surely make it grow upwards, or ascend a bank ;_ for 
that would be hke making a river to run upa hill. * , 
In short, the more we examine the subject, the more we feel 
the want of a principle ‘‘ inherent in vegetable life ” to determine 
the direction of the plant. We see that such a principle must be 
the cause of many of the other phenomena of vegetation, and 
why not also of the phenomenon in question. To what but to 
the operation of such a principle are we to ascribe the move- 
ments of Hedysarum gyrans ; the irritability of the Mimose ; the 
spiral ascent of the twming stem, as being directed to the nght 
or to the left respectively, and never otherwise ; the phenomenon 
of the sleep of plants; and, perhaps, of the Horologiwm Lore ? 
and how shall we account without it for the adaptation of the 
vegetable structure to the wants of the species, as exemplified in 
the hollow stems of the grasses, interrupted with knots ; and the 
hollow but knotless scape of the onion inflated in the middle ; 
together with the growth and maturation of the leaves, flowers, 
and fruit, which are formed complete in all their parts, and 
arranged in the most appropriate order, long before their ulti- 
mate evolution, and totally independent of gravitation, or of the 
position in which art or accident may happen to have placed 
them, or of any other cause that is merely either chemical or 
mechanical? But if gravitation is really the agent that gives 
direction to the root and stem of plants, then, I presume, there 
will be no absurdity in inquiring, whether the upright growth of 
the horns of the stag, and the twisted and spiral growth of the 
horns of the ram, are not the effect of gravitation also; or 
whether the teeth of the upper jaw of a man do not grow down- 
wards, and the teeth of the under jaw upwards, by virtue of 
gravitation. 
I am ready to acknowledge Mr. Knight’s great merit in the 
introduction of several important horticultural improvements, as 
well as in the discovery, or rather in the more complete esta- 
blishment of certain important phytological facts ; but I do not 
think that he has been equally successful in the establishment of 
the several hypotheses which he has advanced for the purpose of | 
explaining the phenomena of vegetation. Perhaps my opinion 
may be singular, but it has not been formed without much 
examination, especially on the subject of the present hypothesis, 
which, I think, | have proved to be not only contradicted by the 
result of Mr. Knight’s own experiments, as well as by a multi- 
plicity of well-known facts ; but even indebted for its plausibility 
to a misapprehension of facts. I am, Sir, 
Kee Your most obedient humble servant, 
P. Kern. 
