The Mode of Inheritance of Semi-Sterility in the Offspring of Certain Hybrid Plants. 313 



Aborted 



ovules 



82 



Peroentage of 



ovules aborted 



17 



Pedigree No. Pods Seeds 



Y 5-ia 78 387 



The number of pods with no aborted ovules was 32. The distal halves 

 of the pods gave onlj^ 9 per cent of aborted ovules. 



The China bean drops more of its early flowers than the other 

 three plants. One plant, taken at random out of a row gi'own on poles 

 in 1912, g-ave: 



Aborted Percentage of 



ovules ovules aborted 



Pedigree No. 



Pods 



Seeds 



C 10 



184 



846 



259 



23 



Fig. 6. 



Median section of ovule from 

 flower of China bean. 



Fig. 5. Photograph of section of ovary 

 from a flower of the Velvet bean, showing 

 an ovule in median section. Micrometer 

 scale in tenths and hundredths of a milli- 

 meter also photographed. 



Most of the aborted ovules in this plant were at the bases of the pods. 

 The distal halves of the pods gave only 6 per cent of ovules aborted. 

 The plant had 51 pods with no aborted ovules. 



Five ovaries of China flowers (the last flowers in the field, early 

 in November) were cut into sections 14 microns thick. Four of these 

 ovaries had all theii- ovules, 23 in number, provided with a complete 

 embrvo-sac (Fig. 6). One ovary however contained 5 ovules with quite 

 aborted embryo-sacs, and 1 ovule with a normal embryo-sac. I assume 

 that in these last flowers, wliich developed during a cool period on a 

 plant covered with ripe pods, there was a physiological abortion of 



