STATE HORTICULTURAL SOCIETY. 79 



such hybrids or crosses have been produced, notably the Cystisno 

 Adami, so well remembered by the readers of Darwin's "Animals and 

 Plants under Domestication." But I think we may say that such 

 crosses or hybrids are of very rare occurrence and exceedingly excep- 

 tional. We do not know of a single instance in which the skill of 

 the grafter can regularly, or even occasionally, produce them, except 

 as a kind of Ihsks naturw. 



But if graft hybrids do occur, thej arise from the immediate 

 place of contact between the cion and the stock, just as an ordinary 

 embryo forms where the sexual elements meet and coalesce in the 

 ovary of the flower, not somewhere else in the mother plant. If 

 there is any essential modification of the cion by the stock, or the 

 reverse, it must come from the commingling of the protaplasm of 

 the two, and this is exceedingly improbable at a distance from the 

 graft. It Would be rash to say, from the teachings of vegetable 

 physiology, that it does not occur; yet I think we may certainly con- 

 clude that it is not a common phenomenon. If there is reason to 

 suppose that graft hybrids or true crosses even between individuals 

 of the same variety are exceedingly exceptional productions, we must 

 infer that this wider influence is still further exceptional. Should it 

 be confidently proved that an essential characteristic of a Porter ap- 

 ple is once changed by grafting on a Red Astrachan stock, this 

 would by no means show that another experiment of the same kind, 

 with all the conditions as nearly alike as possible, would result in the 

 same thing. To make the matter still more uncertain we know that 

 bud variation does sometimes occur on non-grafted plants. The 

 original impress upon the life substance does become modified in 

 ways of which we know nothing. Sports among cultivated plants 

 are not uncommon, yet no one knows how to make them appear by 

 any process of manipulation. So, if a grafted stock should show in- 

 contestible variation in rare instances, we could not be sure the cion 

 caused the change. 



It is, perhaps, necessary here to again exclude the mere changes 

 in vigor shown by plants on different stocks. The stock and cion 

 do have reciprocal influences in the matter of nutrition and pecu- 

 liarities of growth, fruitfulness and the like. A pear tree on pear 

 roots may grow much larger than on quince roots and be several 

 years later in bearing fruit, A feeble rose may develop into mag- 

 nificent proportions on a more vigorous stock. Roots may like- 

 wise be modified in size and vigor by the change of foliage, etc., 

 as a result of grafting, but these roots will nevertheless preserve 

 their usual habit of growth as to direction and mode of branch- 

 ing. A Bartlett pear cion taken from a quince stock and placed 

 on pear roots shows nothing afterwards of the quince influence. 

 The fact is, in the ordinary methods of propagating apples and 

 pears we confidently proceed upon the assumption that the stock 

 has no real and essential influence upon the cion; otherwise it 



