GRAFTING 81 



enzymes. They act as stimulating or repressive 

 agents in connection with various activities of organs 

 of animals and plants. This Morgan City tree prob- 

 ably belongs to the group of "hybrids by grafting." 

 That point cannot be determined accurately without 

 cutting off the grafted top and then noting if sprouts 

 from the pecan stock bear hybrid nuts instead of 

 pecans later, due to a changed hormone perhaps. 



As a rule graft and stock retain their identity, but 

 in some cases the graft changes the stock. The physi- 

 ology of the graft-hybrid is not as yet understood, 

 but we may perhaps speculate upon the possibility of 

 enzymes from the stock or graft exerting an influ- 

 ence upon growing embryonic cells in such a way 

 that they develop in response to influences belonging 

 to both parents. A practical application of the influ- 

 ence of stock upon graft and vice versa was noted by 

 the orange growers of the south who found that the 

 Satsuma orange grafted upon trifoliate orange stock 

 bore solid juicy fruit, while the same variety when 

 grafted upon wild sour orange stock bore fruit which 

 was raggy. 



Every variety of apple produces its own kind of 

 roots without reference to the kind of seedling stock 

 upon which it is grafted, according to the late Pro- 

 fessor John Craig. The scion overrules the natural 

 roots in apples when the budding or grafting is done 

 upon stocks only one or two years of age. This 

 overruling is done evidently by top hormones influ- 

 encing enzyes below, which determine the character 

 of the root growth. Nut trees may act like 



