The whole area of the union is therefore weaker. 



The constant and excessive deposits of these soft roundish cells 

 is what causes the swellings so frequently seen at the point of union 

 in grafts. 



In some cases these round cells form a thin wall of division be- 

 tween the tissues of the growing stock and cion. This was the case 

 with the bud graft illustrated in figure 9, a pear on a quince root, 

 which, after growing three years, broke off with a cleavage almost as 

 clean as the ball and socket of a hip joint. This articulation will be 

 seen filling the middle half of the area of fracture. The surround- 

 ing portions, broken more roughly, are the loose corky tissue which, 

 filling in between the wood and the bark, have formed the large 

 swelling at the point of junction. 



v 







Fig. 10. A defective and broken bud graft. Pear on Quince. 



After a close study of a large number of these defective unions, 

 the writer has reached the opinion that they are almost always due 

 to the incompatibility of stock and cion, as referred to above. It is 

 a common notion among horticulturists that careless or ignorant 

 manipulation — the defective setting of bud or cion — in the grafting 

 will lead to these poor unions. There seems to be little ground for 

 this opinion. If the stock and cion are of varieties which are con- 



