418 GKAFT-HYBRIDS. Chap. XI. 



or segregated in various ways. This tree can be propagated by 

 cuttings, and retains its diversified character. The so-called tri- 

 facial orange of Alexandria and Smyrna 101 resembles in its general 

 nature the bizzarria, and diners only in the orange being of the 

 sweet kind ; this and the citron are blended together in the same 

 fruit, or are separately produced on the same tree ; nothing is 

 known of its origin. In regard to the bizzarria, many authors 

 believe that it is a graft-hybrid ; Gallesio, on the other hand, thinks 

 that it is an ordinary hybrid, with the habit of partially revert- 

 ing by buds to the two parent-forms ; and we have seen that the 

 species in this genus often cross spontaneously. 



It is notorious that when the variegated Jessamine is budded on 

 the common kind, the stock sometimes produces buds bearing 

 variegated leaves : Mr. Rivers, as he informs me, has seen instances 

 of this. The same thing occurs with the Oleander. 102 Mr. Rivers, 

 on the authority of a trustworthy friend, states that some buds of 

 a golden-variegated ash, which were inserted into common ashes, 

 all died except one; but the ash-stocks were affected, 103 and pro- 

 duced, both above and below the points of insertion of the plates 

 of bark bearing the dead buds, shoots which bore variegated leaves. 

 Mr. J. Anderson Henry has communicated to me a nearly similar 

 case : Mr. Brown, of Perth, observed many years ago, in a Highland 

 glen, an ash-tree with yellow leaves ; and buds taken from this tree 

 were inserted into common ashes, which in consequence were affected, 

 and produced the Blotched Breadalbane Ash. This variety has been 

 propagated, and has preserved its character during the last fifty 

 years. Weeping ashes, also, were budded on the affected stocks, 

 and became similarly variegated. It has been repeatedly proved 

 that several species of Abutilon, on which the variegated A. thumps- -nii 

 has been grafted, become variegated. 104 



Many authors consider variegation as the result of disease ; and the 

 foregoing cases may be looked at as the direct result of the inoculation 

 of a disease or some weakness. This has been almost proved to be 

 the case by Morren in the excellent paper just referred to, who shows 

 that even a leaf inserted by its footstalk into the bark of the stock 

 is sufficient to communicate variegation to it, though the leaf 

 soon perishes. Even fully formed leaves on the stock of Abuti- 

 lon are sometimes affected by the graft and become variegated. 

 Variegation is much influenced, as we shall hereafter see, by the 

 nature of the soil in which the plants are grown ; and it does not 



101 'Gard. Chron.,' 1855, p. 628. 199. 



See also Prof. Caspary, in ' Transact. 104 Morren, ' Bull, de l'Acad. R. des 



Hort. Congress of Amsterdam,' 1865. Sciences de Belgique,' 2de series, 



102 Gartner (' Bastarderzeugung,' s. torn, xxviii., 1869, p. 434. Also Mag- 

 611) gives many references on this nus, ' Gesellschaft naturforschender 

 subject. Freunde, Berlin,' Feb. 21, 1871, p. 



103 A nearly similar account was 13 ; ibid., JuDe 21, 1870, and Oct. 17, 

 given by Brabley, in 1724, in his 1871. Also ' Bot. Zeitung,' Feb. 24, 

 'Treatise on Husbandry,' vol. i. p. 1871. 



