The Rev. P. Kxrru on the Origin of Buds. 493 
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. 91 plants 
