FERTILITY IN CICHORIUM INTYBUS 



383 



Table I — Continued 



possible. It is not to be considered that the degree of fertiHty is 

 absolutely determined, and especially in those cases when birds (Ser. 

 12, no. 11) ate all or a part of the seed produced in certain heads. 

 The detailed data, however, make it quite clear that various degrees of 

 self-compatibility may exist. The evidence in this particular is quite 

 identical with that already reported in 1916. In Ser. ii a compara- 

 tively large proportion of plants, 5 out of 19, were self-sterile, but the 

 fertility was low in each case. 



The two plants of Ser. 6 were derived from self-fertilized seed of a 

 plant that was feebly self-fertile and which was the only self-fertile 

 plant that appeared in my crops of this variety previous to 19 16. The 

 two plants were self-sterile. 



Self-Compatibilities and Incompatibilities among Plants of 



THE 1 9 16 Crop of Fi Generation Obtained by Crossing 



A Plant (A) of Wild Stock with Plants of the 



Variety "Red-Leaved Treviso" 



The data for the self-pollinations of this generation are presented 

 in Table 2. The wild white-flowered plant A was the pollen parent 

 for Series 1-4 and the seed parent of Series 5. Five different plants of 

 the 1915 generation of "red-leaved Treviso" were concerned in the 

 parentage, as indicated in the table. The uncertainties of securing 

 compatible cross-pollinations among self-sterile plants (Stout, 1916, 



