GRAFTING 411 



forms of tissues, its own mode of secondary growth, 

 its own formation of bark, and maintains its strong 

 individuality." 



Strasburger points out "that the scion and stock do 

 exert some influence upon one another, for when annual 

 plants are grafted upon biennial or perennial stocks, 

 they attain an extended period of existence." He 

 also adds that "in special cases they do mutally exert, 

 morphologically, a modifying effect upon each other 

 (graft hybrids)." 



McCallum gives a number of interesting examples of 

 modifications in scion and stock following grafting. 

 " In the leaves of Epiphyllum are found certain albumen 

 bodies not found in the leaves of the related plant 

 Peireskia. Mitosch grafted Epiphyllum scions upon 

 Perireskia stocks, and in the leaves which subsequently 

 developed upon the latter found similar bodies." 



The most interesting graft-hybrid, and the only one it 

 seems worth while to mention, is the Cytisus adami, 

 which is a most striking example of what may happen 

 when grafting is successful. The Cytisus vulgare is a 

 large tree bearing racemes of yellow flowers; Cytisus 

 purpureus a shrub of small size bearing racemes of 

 small purple flowers. In 1826, J. L. Adam tried the ex- 

 periment of grafting the latter upon the former and 

 produced a surprising hybrid which grew into a large 

 tree upon which appeared large numbers of the usual 

 yellow racemes of Cytisus vulgare, large numbers of 

 reddish racemes of equal size, and, what was most pecu- 

 liar, distributed over the tree like gay parasites, there 

 were groups of small boughs upon which were numbers 

 of the small purple racemes of Cytisus purpureus. 

 Presumably such an effect could only be brought about 

 through a partial fusion of the protoplasts of stock and 

 graft in the callus formed during the healing of the 

 graft wound. Interesting graft-hybrids have also been 

 produced by Winkler. 



