FERTILITY IN CICHORIUM INTYBUS 
Discussion and Conclusion 
The sporadic development of self-compatibility giving self-fertility 
among the progeny of self-sterile lines of descent is in decided evidence 
in the cultures reported above. No doubt if a larger number of the 
''red-leaved Treviso" variety had been grown and tested, more than 
one self-fertile plant would have been found previous to the crop of 
1916. However, they were not found and the variety was kept in 
pedigreed cultures by crossing self-sterile plants. 
Self-compatibility is therefore a characteristic that was new in 
expression, at least to the particular and immediate line of descent 
involved. A total of loi plants of the 1916 crop had three generations 
of ancestry known to be self-sterile; of these 11 plants were self-fertile. 
There is, therefore, much in the occurrence of these plants 
that suggests discontinuous variation or mutation. However, the 
fertilities of these self-fertile plants vary. They grade over to 
complete self-sterility. The variation in the self-fertility of plants 
grown from self-fertile parents (Stout, 1916, Table 6) is much more 
continuous and is indicative that the irregular and somewhat dis- 
continuous variation seen in the intensity of fertilities is only an 
apparent one due to the few cases observed. 
It is to be noted that there have been scarcely any attempts made 
to study the progeny of self-sterile plants in species and varieties 
known to be strongly self-sterile by continued inbreeding in pedigreed 
lines of descent. Compton (1912, 191 3) has reported that in Reseda 
odorata "self-sterile plants when bred inter se throw self-sterile offspring 
only," but he has not published data regarding the number of such 
families, the number of plants, or the number of generations tested. 
East (191 5) has reported that the inter-specific hybrids between 
Nicotiana forgetiana and N. alata grandiflora have been completely 
self-sterile for four generations, and that a total of over 500 plants were 
tested. Data on the behavior of the parent plants, or even of the two 
parent species, were evidently not obtained. Correns (1912, 1913) 
was especially interested in the study of cross-incompatibilities and 
evidently tested the self-fertility of only 13 of the total of 60 sister 
plants obtained by crossing two self-sterile plants of Cardamine 
pratense. Of these, however, three plants appear to have been self- 
fertile. 
In view of the prevalence of self-incompatibilities in many plants 
of economic importance, such as cabbage, rye, apple, plum, prune. 
