Chap. IX. GRAFT-HYBRIDS. 423 



Any one who will attentively consider the abstract now 

 given, of the experiments made by many observers in several 

 countries, will, I think, be convinced that by grafting two 

 varieties of the potato together in various ways, hybridised 

 plants can be produced. It should be observed that several 

 of the experimentalists are scientific horticulturists, and 

 some of them potato-growers on a large scale, who, though 

 beforehand sceptical, have been fully convinced of the possi • 

 bility, even of the ease, of making graft-hybrids. The only 

 way of escaping from this conclusion is to attribute all the 

 many recorded cases to simple bud- variation. Undoubtedly 

 the potato, as we have seen in this chapter, does some- 

 times, though not often, vary by buds; but it should be 

 especially noted that it is experienced potato-growers, whose 

 business it is to look out for new varieties, who have expressed 

 unbounded astonishment at the number of new forms produced 

 by graft-hybridisation. It may be argued that it is merely 

 the operation of grafting, and not the union of two kinds, 

 which causes so extraordinary an amount of bud- variation ; 

 but this objection is at once answered by the fact that potatoes 

 are habitually propagated by the tubers being cut into pieces, 

 and the sole difference in the case of graft-hybrids is that 

 either a half or a smaller segment or a cylinder is placed in 

 close opposition with the tissue of another variety. Moreover, 

 in two cases, the young stems were grafted together, and the 

 plants thus united yielded the same results as when the tubers 

 were united. It is an argument of the greatest weight that 

 when varieties are produced by simple bud- variation, they 

 frequently present quite new characters ; whereas in all the 

 numerous cases above given, as Herr Magnus likewise insists, 

 the graft-hybrids are intermediate in character between the 

 two forms employed. That such a result should follow if the 

 one kind did not affect the other is incredible. 



Characters of all kinds are affected by graft hybridisation, 

 in whatever way the grafting may have been effected. The 

 plants thus raised yield tubers which partake of the widely 

 different colours, form, state of surface, position and shape 

 of the eye of the parents ; and according to two careful ob- 

 servers they are also intermediate in certain constitutional 



