nvbom: vegetativelv propagated species 



269 



Figure 4. — X-ray-induced tissue recombination leading to chlorophyll- 

 deficient shoot in the chimaerical sport Striped Williams. 



fruits, Figure 6, a common effect of reduced seed formation in pears 

 (9). In the seedless fruits, shown on both sides of a normal pear in 

 Figure 7, only the empty seed coats are to be found in the carpels. 

 The fruit-set of this seedless type did not look markedly influenced. 

 Another change, probably also without practical interest, is the 

 small-flowered mutant shown in Figure 9, Cox's Pomona gamma- 

 irradiation. 



Increased russeting, i.e., a rougher fruit skin, obviously is a 

 rather common change both spontaneously and after treatment. It has 

 been induced in the pear varieties Seigneur d'Esperen, Graf Moltke, 

 and Williams, as also in the apple variety Belle de Boskoop. 



Of more commercial interest are the red-colored changes of 



