96 NUT GROWING 



of a corky layer over the wound surface between 

 stock and scion. Corky cells introduce a mechanical 

 obstacle to union. 



In the epidermis of all parts of the plant which 

 are exposed to the air are minute openings called 

 stomata, in addition to the larger lenticles. It is the 

 knowledge of this fact perhaps that has prevented 

 botanists and horticulturists in the past from cover- 

 ing a graft completely with a material that is im- 

 pervious to air and moisture. In actual practice I 

 have found that this interference with respiration of 

 the graft is not of practical importance. The respira- 

 tion of the stock attends to the matter of metabolism 

 and the scion is taken care of. Reparative and 

 nutrient materials together with enzymes for stimu- 

 lating growth are sent into the scion from the stock 

 irrespective of interference with respiration of the 

 scion itself. 



Experimentally, I have used scions from half an 

 inch in length up to some that were beyond two feet 

 in length, all of which grew when covered with im- 

 pervious paraffin. At the moment of writing I re- 

 gret not having experimented with scions several 

 feet in length. This will be done next season. In 

 the north it is not necessary to cover paraffined 

 grafts with a paper bag. 



The extent to which the new method will change 

 our ideas on the subject of fruit tree grafting can- 

 not be foretold. In August of the present year of 

 writing my gardener accidentally broke off the top 

 of a young dwarf pear tree. This top was kicked 



