144 STATE HORTICULTURAL SOCIETY. 



of so-called graft-hybrids which have proved permanent are either cases 

 of variegation, or of varieties which there is reason to believe are the 

 result of bud variation or other causes aside from grafting. It now 

 remains to consider whether any of the lesser variations attributed to 

 grafting are permanent. We know that changes induced by soil and cli- 

 mate are often more or less permanent in their nature. 



It may be well, first, to recall the theory of Thomas Andrew Knight 

 that all plants propagated by grafting, or division of the original plant 

 in any way, tend to degenerate. This theory was stoutly denied by Lind- 

 ley and others, but is still held by many to be at least probable. 1 



To obviate any injurious effect of inferior stocks, Downing recommends 2 

 in accordance with Van Mons' theory, that seeds for the production of new 

 varieties be taken only from ungrafted trees, though he admits that good 

 varieties have originated from grafted fruit. Mr. Arnold of Michigan 

 also believes that in making crosses the natural stock, in apples and pears, 

 which have been grafted, may exert a bad influence. 3 



In his " Fruits and Fruit Trees of America,'' first edition, 1845, page 5, 

 Downing says: " Among the great number of seedling fruits produced in 

 the United States, there is found occasionally a variety, perhaps a plum or 

 a peach, which will nearly always reproduce itself from seed. From some 

 fortunate circumstance in its origin, unknown to us, this sort, in becoming 

 improved still retains strongly this habit of the natural or wild form, and 

 its seeds produce the same. We can call to mind several examples of this; 

 fine fruit trees whose seeds have established the reputation in the neighbor- 

 hood of fidelity to the sort. But when a graft is taken from one of these 

 trees and placed upon another stock this grafted tree is found to lose its 

 singular power of producing the same by seed, and becomes like all other 

 worked trees. The stock exercises some, as yet unexplained, power in 

 dissolving the strong natural habit of the variety, and it becomes, like its 

 fellows, subject to the laws of its artificial life." 



In the edition of 1869, the author says that this doctrine has "perhaps 

 no foundation in fact, " and has been neither established nor disproved by 

 experiment; and adds, "observation of many years leads to the belief that 

 the mere engrafting of a variety upon another stock in no way affects its 

 habit or capacity for reproducing itself. " 



Darwin gives grafting as one of the causes which may induce variability 

 in plants. He says * " Cabanis (quoted by Sagert, "Pomological 

 Physiology,"' 1830, page 43) asserts that when certain pears are grafted 

 on the quince their seeds yield more varieties than do the seeds of the 

 same variety of pear when grafted on the wild pear. " 



And again 5 he quotes the statement of M. Cardanmalle, made in 1848: 

 " The Lalande variety of the walnut tree leafs between April 20 and May 

 15, and its seedlings invariably inherit the same habit; while several other 

 varieties of the walnut leaf in June. Now, if seedlings are raised from 

 the May-leafing Lalande variety, grafted on another May-leafing variety, 

 though both stock and graft have the same early habit of leafing, yet the 

 seedlings leaf at various times, even as late as the fifteenth of June." 



1 See, for example, Asa Gray, American Journal of Science, vol. XXXVI, 1863, p. 431. 



2 Fruits and Fruit Trees of America (1869), p. 7. 



3 W. J. Beal, Report Michigan Board of Agriculture. 1S76, p. 211. 

 1 Animals and Plants under Domestication, vol. II, page 312. 



5 lb., page 313. 



