Chap. XI. 



OF REPRODUCTION AND VARIATION 



395 



plants are grown; and it does not seem improbable that whatever change 

 in the sap or tissues certain soils induce, whether or not called a disease, 

 might spread from the inserted piece of bark to the stock. But a change 

 of this kind cannot be considered to be of the nature of a graft-hybrid. 



There is a variety of the hazel with dark-purple leaves, like those of 

 the copper-beech: no one has attributed this colour to disease, and it 

 apparently is only an exaggeration of a tint which may often be seen on 

 the leaves of the common hazel. When this variety is grafted on the 

 common hazel, 112 it sometimes colours, as has been asserted, the leaves 

 below the graft ; but I should add that Mr. Rivers, who has possessed 

 hundreds of such grafted trees, has never seen an instance. 



Gartner 113 quotes two separate accounts of branches of dark and white- 

 fruited vines which had been united in various ways, such as being split 

 longitudinally, and then joined, &c. ; and these branches produced distinct 

 bunches of grapes of the two colours, and other bunches with grapes 

 either striped or of an intermediate and new tint. Even the leaves in one 

 case were variegated. These facts are the more remarkable because 

 Andrew Knight never succeeded in raising variegated grapes by fertilising 

 white kinds by pollen of dark kinds ; though, as we have seen, he ob- 

 tained seedlings with variegated fruit and leaves, by fertilising a white 

 variety by the variegated dark Aleppo grape. Gartner attributes the 

 above-quoted cases merely to bud- variation ; but it is a strange coincidence 

 that the branches which had been grafted in a peculiar manner should 

 alone have thus varied ; and H. Adorne de Tscharner positively asserts 

 that he produced the described result more than once, and could do so at 

 will, by splitting and uniting the branches in the manner described by him. 



I should not have quoted the following case had not the author of ' Des 

 Jacinthes' 114 impressed me with the belief not only of his extensive know- 

 ledge, but of his truthfulness : he says that bulbs of blue and red hyacinths 

 may be cut in two, and that they will grow together and throw up a 

 united stem (and this I have myself seen), with flowers of the two colours 

 on the opposite sides. But the remarkable point is, that flowers are some- 

 times produced with the two colours blended together, which makes the 

 case closely analogous with that of the blended colours of the grapes on 

 the united vine-branches. 



Mr. R. Trail stated in 1867, before the Botanical Society of Edinburgh 

 (and has since given me fuller information), that several years ago he cut 

 about sixty blue and white potatoes into halves through the eyes or buds, 

 and then carefully joined them, destroying at the same time the other eyes. 

 Some of these united tubers produced white, and others blue tubers; 

 and it is probable that in these cases the one half alone of the bud grew. 

 Some, however, produced tubers partly white and partly blue ; and the 

 tubers from about four or five were regularly mottled with the two colours. 

 In these latter cases we may conclude that a stem had been formed by 

 the union of the bisected buds ; and as tubers are produced by the en- 

 largement of subterranean branches arising from the main stem, their 



112 Loudon's ' Arboretum,' vol. iv. p. 

 2595. 



113 •Bastarderzeugung/ s. 619. 



114 Amsterdam, 1768, p. 124. 



