THE RECIPROCAL INFLUENCES OF STOCK AND CI ON 555 



and that the pear does better on the apple than the apple on the pear. 

 Baltet states that medlar does well on quince but the quince fails on 

 medlar; the same holds true with quince on hawthorn and vice versa. 

 Sweet cherry on sour cherry is more successful than the reverse 

 combination.^^ 



Tufts states: " . . .it has been the experience of certain growers 

 in the Vacaville section, California, that practically all the varieties of 

 Japanese plums will work satisfactorilj'- with domestica varieties. How- 

 ever . . . the insertion of European plum scions on Japanese plums 

 does not always result in a satisfactory union. It has been found that 

 plum orchards, where worked over to Japanese varieties, could not be 

 worked back to European varieties unless all the Japanese wood was 

 taken from the tree."^*^ 



Similar contrasts in reciprocal grafts occur in the combination of 

 various evergreen on deciduous plants. There are numerous instances 

 of at least passable success in grafts of this sort, but the inverse combina- 

 tion, deciduous on evergreen, is almost invariably a failure. 



Congeniality and Adaptability Distinguished. — Distinction should be 

 made between congeniality and adaptability. The former term refers 

 to the degree of success of the union between stock and cion; the latter 

 term to the relation of the combined parts to environment, most often 

 to soil and climate. Husmann's conception of perfect congeniality 

 in grapes is a condition in which "a variety grafted on another behaves as 

 if the stock were grafted with a scion of itself, the union being perfect and 

 the behavior of the vine the same as that of an entire ungrafted plant. "^* 

 He states also, "When both stock and scion are suited to the conditions, 

 but will not thrive when grafted, congeniality is lacking." Further: 

 "The adaptability of varieties to soil, climates and other conditions can 

 often be closely forecasted, but congeniality has to be determined by 

 actual test." 



Congeniality and adaptability are sometimes differentiated only 

 with difficulty, as is shown by the following quotation from Blunno:^^ 

 "In France, however, it was found that the yield of the French vines 

 grafted on du Lot was low; our experience is exactly the same at the 

 Viticultural Station, Howlong [New South Wales] — the wine-grape 

 varieties grafted on this stock are the poorest croppers of all. In Sicily, 

 however, the affinity between the native European vines and the Rupe- 

 stris du Lot seems to be perfect and the yield is heavy. In this state the 

 principal wine-grapes are French varieties and this explains how our ex- 

 perience with vines on Rupestris du Lot as poor croppers is similar to 

 that in France." 



The most congenial combination is not necessarily the most successful, 

 as is shown by an experience in New York, citied by Bailey.^ Plum 

 and peach stocks failed to make satisfactory unions with the apricot 



