ON THE REPRODUCTION OF BUDS. 121 



with the preceding facts, is adduced to prove only that the reproduced 

 buds of these plants are not generated by the cortical substance of the 

 root : and 1 shall proceed to relate some experiments on the apple, and 

 pear, and plum-tree, which I conceive to prove that the reproduced 

 buds of those plants do not spring from the medulla. 



Having raised from seeds a very considerable number of plants of each 

 of these species in 1802, I partly disengaged them from the soil in the 

 autumn, by digging round each plant, which was then raised about two 

 inches above its former level. A part of the mould was then removed, 

 and the plants were cut off about an inch below the points where the 

 seed-leaves formerly grew; and a portion of the root, about an inch 

 long, without any bud upon it, remained exposed to the air and light. 

 In the beginning of April I observed many small elevated points on the 

 bark of these roots, and, removing the whole of the cortical substance, 

 I found that the elevations were occasioned by small protuberances on 

 the surfaces of the alburnum. As the spring advanced, many minute 

 red points appeared to perforate the bark ; these soon assumed the cha- 

 racter of buds, and produced shoots, in every respect similar to those 

 which would have sprung from the organized buds of the preceding year. 

 Whether the buds thus reproduced derived any portion of their component 

 parts from the bark or not, I shall not venture to decide ; but I am much 

 disposed to believe that, like those of the potato, they sprang from 

 the alburnous substance solely. 



The space, however, in the annual root, between the medulla and the 

 bark is very small ; and therefore it may be contended that the buds in 

 these instances may have originated from the medulla. I therefore 

 thought it necessary to repeat similar experiments on the roots and 

 trunks of old trees, and by these the buds were reproduced precisely in 

 the same manner as the annual roots : and therefore, conceiving myself 

 to have proved in a former memoir*, that the substance which has been 

 called the medullary process does not originate from the medulla, I must 

 conclude that reproduced buds do not spring from that substance. 



I have remarked in a paper, laid before the Royal Society in 

 the commencement of the present year, that the alburnous tubes, at 

 their termination upwards, invariably join the central vessels, and that 

 these vessels which appear to derive their origin from the alburnous 

 tubes, convey nutriment, and probably give existence to new buds 

 and leaves. It is also evident, from the facility with which the rising 

 sap is transferred from one side of a wounded tree to the other, 

 * See above, the Paper No. III. 



