SCT. III. CHEMICAL PHENOMENA. *27 



sition to the power of gravitation, bend itself up- 

 wards till it reaches the bough, and insinuate itself 

 into the very substance of the bark above it ? Till 

 these questions can be satisfactorily answered they 

 must be regarded as presenting an insurmountable 

 obstacle to the adoption of Mr. Knight's hypothesis. 



If I were to offer a conjecture in addition to the Ascribed 

 many that have been already offered, I should say tive prm- 

 that the invincible tendency of the radicle to fix Clp e 

 itself in the earth or other proper soil ; and of the 

 plumelet to ascend into the air, arises from a power 

 inherent in the vegetable subject, analogous to what 

 we call instinct in the animal subject, infallibly 

 directing it to the situation best suited to the ac- 

 quisition of nutriment and consequent develope- 

 ment of its parts. And upon this hypothesis we 

 include all varieties of plants whatever, parasitical 

 as well as others ; for let them attach themselves to 

 whatever substance they will, to them it still affords 

 a fit and proper soil. 



SECTION III. 

 Chemical Phenomena. 



THE chemical phenomena of germination con- As effect 

 sist chiefly in the changes that are effected in the 

 nutriment destined for the support and develope- 

 ment of the embryo till it is converted into a plant. 

 It was already shown that this nutriment either 



