] 00 Self- Incompatibility in Hermaphrodite Plants 



others. With only one exception the self-compatibility was feeble. It 

 is clear that self-compatibility exhibited no tendency to develop as an 

 " end season " fertility. 



A most striking type of seed sterility was seen in the considerable 

 number of plants that produced pods which were empty. In the feebly 

 self-fertile plants, as a rule, the few good seeds that were developed were 

 located in the upper end of the capsules. The considerable number of 

 poor seed present both in pods containing few seeds, and in empty pods, 

 suggests tha't incompatibility may operate after fertilization, producing 

 embryo abortion. The results here obtained also suggest that some 

 seedless pods may develop as a direct result of the stimulus of pollen 

 tube growth, and more obviously that the size of pods bears a relation 

 to the number of ovules fertilized. 



Nicotiana Forgetiana Hyb. Hort. 



Series 1. In 1917, the writer, assisted by Miss Helene Boas (now 

 Mrs. Cecil Yampolsky), tested the self-compatibility of 58 plants of 

 N. Forgetiana Hyb. Hort. Controlled self-pollinations were made by 

 hand on successive dates using the same method employed for Verhascum 

 phoeniceum, except that bags were shifted from branch to branch. In 

 all cases the pollinations were begun during the first days of bloom. 



On the basis of their self-compatibility and incompatibility these 

 plants may be grouped in three classes. 



(1) Eleven plants were highly self-fertile from the first day of 

 controlled self-pollination. There were only 3 flowers out of 95 selfed 

 that failed to produce pods. The capsules were large and well filled 

 with seeds. As soon as it was found that a plant was self-fertile no 

 further controlled pollinations were made. 



(2) Eight plants were feebly self-compatible. Capsules were pro- 

 duced in relatively few of the selfed flowers, and these were small and 

 contained few seeds. For 6 plants some pods developed in flowers of 

 the first date of selfing ; in the other 2 plants pods were formed from 

 flowers of the second date of selfing. All these plants, however, were 

 partially self-compatible during the first days of bloom. 



(3) Thirty-nine plants were completely self-incompatible to all 

 controlled selfings made, which were extended to well past the climax 

 of bloom in all cases and for 10 plants the selfings were continued to 

 the last date of bloom. 



The plants of this series were grown from commercial seed and there 

 was considerable variation in the colour of the flowers. Several con- 



