The Mode of Inheritance of Semi-Sterility in the Offspring of Certain Hybrid Plants. 311 



times in such unhealthy anthers a few giant pollen-grains are found, and 

 this has also occasionally been seen in unhealthy anthers of the China 

 bean.) But the pollen in healthy anthers is as good as that of the 

 Velvet bean, and the same plants that have some flowers with bad 

 pollen have others with good pollen. On October 9, 1912, two flowers 

 were examined. One had 342 good to 50 more or less abnormal or 

 empty grains in several fields of the microscope, and the other showed 

 150 good to 9 more or less empty. On August 12, 1913, two flowers 

 from each of 22 plants grown in the field were examined. The flowers 

 of 18 plants had good pollen; those from 4 plants were more or less 

 diseased with discolored anthers, and their pollen was more or less ab- 

 normal. On August 15, 1913, pollen from flowers of 4 plants on poles 

 was found good. On September 1, 1913, the pollen from one plant was 

 found to be good. 



Pollen of the China beau is usually good: but, on October 9, 1912, 

 the last two flowers were examined from a row of China bean plants 

 heavil}' laden with pods. In one flower, 300 good grains were counted 

 to 114 more or less empty; and, in the other flower, about as many 

 grains were more or less empty. Such a large proportion of empty 

 grains has never been seen again. On August 15, 1913, flowers of 

 3 plants were examined, two of which had good pollen, and the other 

 more or less of unhealthy grains. On August 23, 1913, of 9 flowers 

 examined, 6 had good pollen, and 3 were more or less unhealthy. On 

 September 1, 1913, the flowers of 5 plants were examined, and had aU 

 good poUön. The bad state of the pollen in certain flowers of the China 

 bean is accidental, for other flowers on the same plant may have normal 

 pollen. The China flowers, like those of the Yokohama, are more af- 

 fected by the damp of the Florida rainy season than are the flowers 

 of the Velvet and Lyon which blossom later. 



To sum up: Pollen from healthy flowers of the Velvet, 

 Lyon, Yokohama, and China plants contains nearly 100 per 

 cent of good grains. 



Ovules of Parent Plants. 

 Abortion of embryo-sacs before fertilization is of course a different 

 thing from the non- development of ovules with perfect embryo-sacs, 

 whether this non-development results from lack of fertilization or some 

 other cause. This parallels to a certain extent the difference between 

 "fecundity" and "fertility" recognized in animals by Pe.\bl (11). Eight 

 young ovaries from flowers of the Velvet bean (pedigreed line) were cut, 



