The Rev. P. Keith on the Origin of Buds. 42S 



Also the alburnum, according to Mr. Knight, possesses the 

 power of regenerating buds. A number of plants of the Apple, 

 Pear and Plum, which were raised from seed in the spring of 

 1802, were again cut down to the collar in the autumn with 

 part of the root exposed. In the beginning of the following 

 spring, protuberances were observed on the bark of the ex- 

 posed roots, which were found to be processes issuing from the 

 alburnum. They were incipient buds, and were ultimately pro- 

 truded into shoots. Experiments upon the stem and root of 

 aged trees gave the same result; establishing, as Mr. Knight 

 thinks, the position, that the alburnum, or the proper juice de- 

 posited in it, possesses the peculiar property of the organizing 

 of buds ; whence it follows, as a corollary, that the origin of 

 any bud is not more deeply seated in the stem than the layer of 

 alburnum from which it is protruded into a shoot. 



This common doctrine of Du Hamel and of Knight, and I 

 might add of Mirbel also, is combated by a late writer on the 

 subject of Vegetable Physiology ; who contends, in direct op- 

 position to their theory, that all buds protruded from the sur- 

 face of the plant, at whatever period of its growth, have been ori- 

 ginally formed at the centre of the stem or branch on which 

 they appear ; that is, in the original or annual shoot ; and have 

 been pushed outwards horizontally through every additional 

 layer of alburnum while yet in a soft state, though it requires 

 some peculiar excitement to protrude them into shoots, which 

 may not occur till after a period of many years *. The bud in 

 its progress outwards is represented as leaving behind it a pale 

 streak of parenchyma indicating its path, which is in the di- 

 rection of the medullary rays, and very perceptible in a trans- 

 verse section of the Willow taken near the place of the pro- 

 trusion of a young shoot. This rule can apply only to woody 



* Library of Useful Knowledge. 



VOL. XVI. 3 I plants 



