stout: pollinations in cichorium intybus 405 



self-fertility appears in different degrees of intensity in different 

 plants, and that there is very irregular and sporadic inheritance 

 both of the character as such and of the degree of its expression, 

 if the two can in any sense be separated. The character of self- 

 fertihty (and that of cross-fertiHty as well) appears w^ith different 

 degrees of intensity whether in offspring from crossed self-sterile 

 plants or from inbred self-fertile plants. That these differences 

 are in many cases real and not due to the accidents of experimental 

 conditions is, I believe, indicated by the results. The conclusion 

 is inevitable that the quality of self-fertility is different in intensity 

 in the various plants. That such differences are really expressive 

 of internal constitutional conditions places the expression of self- 

 fertility quite on the same basis with the fluctuating variations 

 observed in practically all characters which have been studied 

 quantitatively. 



The studies of the heredity of self-fertility in chicory show 

 that plants most strongly self-fertile do not give offspring all of 

 which are self-fertile, even after two generations of pedigreed 

 culture. In other words, self-sterility, which is strongly in evi- 

 dence in the parent strains and in Cichorium in general, tends 

 strongly to reappear in spite of repeated selections of self-fertile 

 plants. Neither is there a direct correlation between the degree 

 of fertility exhibited by parents and their offspring. 



It is very obvious that there can be no simple numerical ex- 

 pression descriptive of the hereditary behavior of fertility and 

 sterility in chicory and, as I have shown, a careful study of Correns' 

 data leads to the conclusion that his actual observations do not 

 support the conclusions indicated in his formulae. The rather 

 general statements of Lotsy ('13) regarding the Fo generation of 

 Baur's hybrids between Antirrhinum molle and A. majus indicate 

 great variation in regard to self-sterility as in all other characters. 

 He states regarding the progeny of one of these, " II y a des plantes 

 auto-steriles et des plantes auto-fertiles, de sorte que Ton pent 

 dire avec raison qu'il n'y a pas deux plantes identiques parmi les 

 255 individus obtenus en Fo" (p. 420). In view of this fact, the 

 opinions of Baur can hardly be considered, while those of Compton 

 can not be seriously considered until the data are at hand. For 

 the explanation of the causes of self-sterility in chicory, I am 

 convinced that we must look most especially to the type or grade 



