56 



HeterostjfUsm in Oxab's 



necessary, owing to the degree of self-sterility. The risk incurred was 

 slight, and will be referred to later. In mid and short females, however, 

 the tiers of ripe anthers above the level of the stigma were always 

 carefully removed before the foreign pollen was administered. In the 

 controls for this procedure no seed set. In male parents pollen at 

 a higher level than that used was removed in a similar manner. 



Unless otherwise stated, the cross denoted by "Long x Mid," 

 " Mid X Short," etc., is the fertile cross between the two forms, that 

 is, Long-styled % x poUen from long stamens of Mid-styled ; or Mid- 

 styled $ x pollen from mid stamens of Short-styled, etc. 



Results. 



Four generations have been raised. The results of the crosses 

 Long X Mid, and Long x Short, in the four years, together with 

 their reciprocals, are given in Table I and Table II. 



Totals 138 137 



Reciprocals added together:— 



209 



205 



Totals 



203 



191 



151 



15G 



