422 The Rev. 'P. Keith on the Origin of Buds. 



ground produced roots, and the part passing through the earth 

 contained in the barrel produced also roots ; but the other 

 two portions produced branches. It was of little consequence 

 whether the cuttings were inserted in the ground by the upper 

 or under extremity, as relative to their original growth, and 

 they vegetated even when made to pass through the barrel ho- 

 rizontally. Hence Du Hamel concluded that germs both of 

 the root and branch are dispersed throughout the whole extent 

 of the plant, and are developed as the exigency of the case 

 requires*. 



Others have contended that buds are generated only from the 

 plexus of the vessels of the inner bark ; because, perhaps, it is 

 from the inner bark that the union of the graft and stock is 

 effected in the well-known operation of grafting. 



Mr. Knight seems to have embraced the opinion of Du Hamel 

 with some slight modifications. I do not mean to say that he 

 has adopted the appellation, or even the notion of pre-organized 

 germs. But he contends that buds are generated in the albur- 

 num by means of the agency of the descending proper juice ; 

 and thus dispersed, as we may infer, over the surface of the 

 whole plant. His proof is as follows : — The runners connecting 

 the tubers of a potatoe with the root were intersected and im- 

 mersed by both portions in a decoction of logwood. The de- 

 coction passed along in both directions. But it was in the di- 

 rection of the tubers that the proof wanted was elicited. For 

 there, the decoction was found to have passed through an ela- 

 borate plexus of vessels between the bark and alburnum, which 

 was seen to approach the skin at the base of the buds-f*. Hence 

 it was inferred that buds are formed by the agency of the de- 

 scending proper juice in its passage through the vessels of the 

 inner bark. 



* Phi/s. des Arb. liv. iv. chap. v. f Phil. Trans. 1803, p. 289- 



4 Also 



