Rev. P. Keith on Phytological Errors, with Admonitions. 207 



He knew merely the laws by which a certain principle acts, 

 and he gave it a name. Beyond that he knew nothing. The 

 same is the case with the physiologist who talks of a vital 

 principle, and with the phytologist who ascribes the descent 

 of the radicle to a cause analogous to that of animal instinct. 

 He knows very well that he is ignorant of the cause any 

 further than as producing effects that can result only from the 

 exertion of the vital energies of the plant; and to the energies 

 thus exerted he gives the name of instinct. The best and 

 most acute of our phytologists have felt the strong leaning that 

 exists in the human mind to the admission of some such prin- 

 ciple. What says Dutrochet in his Observations sur la Motilite 

 des Vegetans? " En voyant cette diversite de moyens employes 

 pour parvenir a un meme fin, on serait presque tente de croire 

 qu'il existe la une intelligence secrete qui choisit les moyens 

 les plus convenables pour accomplir une action deter minee." 

 (p. 132.) 



For myself, I have abandoned the use of the term instinct 

 entirely ; not because the admission of vegetable instinct is a 

 confession of our ignorance of the cause, — for it is better to 

 confess our ignorance of a cause than to adduce a false one, — 

 but because it is a term calculated to mislead the phytological 

 student, as being so long usurped by the zoologist, and a 

 term, the legitimate use of which seems to me to be that of 

 the denoting of the act of an individual being regarded as 

 sentient, rather than that of the denoting of the growth of any 

 organ or fabric, whether animal or vegetable. Hence, as I 

 disclaim the doctrine of vegetable sensation *, I disclaim, of 

 necessity, that of vegetable instinct also. 



Still I cannot adopt the opinion of those who ascribe the 

 descent of the radicle merely to the force of gravitation. To 

 me the phenomenon seems to be essentially a vital process, 

 which the phytologist is not to confound with any process 

 that is essentially either chemical or mechanical. This is an 

 error, against the commission of which M. De Candolle is at 

 great pains to guard his reader in his Considerations Frelimi- 

 nairesf, and yet, after all, he no sooner finishes his admoni- 

 tions than he seems to me to fall into it himself; for he an- 

 nounces his adoption of Mr. Knight's theory of the descent of 

 the radicle, — that is, the accounting for a vital phenomenon 

 upon a principle merely mechanical f. 



It is not my intention to enter into the merits of Mr. Knight's 

 hypothesis at present : a more convenient season may arrive. 

 What I have to remark now is, that M. De Candolle, on what 



* Phil. Mag. and Annals, N.S., April 1832. 



t Ptys. Feget., torn. i. p. 7- % Ibid., torn. i. p. 30 ; ii. p. 821. 



