114 Self-Incompatihility in Hefmaphrodite Plants 



gives the number of flowers per head expressed as a denominator and the 

 number of seed obtained as the numerator of a fraction. (Such data show 

 that the variations in number of seed per head are quite independent of 

 the number of flowers per head.) Data for No. S3 give comparative results 

 of hand and autonomous self-pollination, which are typical of the evi- 

 dence that careful self-pollination by hand does not increase self- 

 fertility over autonomous selfing. 



The data for No. 50 include for comparison the results of the controlled 

 cross-pollinations of 10 heads, and are quite typical of the abundant 

 evidence obtained which shows that feebly self-compatible or strongly 

 self-incompatible plants are highly productive of seed to compatible 

 crosses made on the same dates of bloom. 



Series R 12-11-16- . All of the 103 seed obtained from the self- 

 pollinations of the parent were planted. Sixty-nine germinated, but 

 possibly as many as 20 embryos had been injured at the time seed was 

 examined to determine if embryos were present. Of the 60 plants 

 tested for self-fertility, 16 were self-incompatible and 44 were self-com- 

 patible. 



The data given for No. 37 in Table III include results of self- 

 pollinations by hand for 10 heads, and for all heads the numbers of 

 flowers and seeds are expressed in the form of a fraction. 



General summary. Table IV presents a grand summary of the 

 various crops of the variety red-leaved Treviso with the pedigree 

 indicated and the distribution of the individual fertilities given. As 

 there shown the variety was kept in culture for the first three years 

 (1914, 1915, 1916) by crossing self-incompatible plants. The first plant 

 found to be self- fertile was one of the 1915 crop but it was very feebly 

 self-fertile and the two offspring gi'own from its seed were self-incom- 

 patible. Among the 1916 crop grown from self-incoApatible parentage, 

 there were 11 plants which were self- fertile to some degree and of these 

 4 were highly self-fertile. 



The subsequent generations descended from self-fertile plants, and 

 the study of fertilities in them constitutes a test for the heredity of self- 

 compatibility that arose sporadically after three generations of self- 

 incompatible parentage. Three lines were grown in the /j, and two 

 families were continued into the /o. 



The proportion of plants that were self-fertile was decidedly increased 

 in the /j and was still larger in the /g. In both families of the I^ there 

 was also an extension in the range of self-fertilities. 



The two families grown into the I^ exhibit some differences in self- 



