100 Fertility in Cichorium intybus 



Conclusions. 



1. Self- and cross-incompatibilities in chicory develop independently 

 of either (a) anatomical incompatibility with its marked structural 

 differences and adaptations for cross-pollination ; or (b) embryo abortion, 

 at least of the sort that is due to the malnutrition of embryos by the 

 parent plant, and which in many fruit-bearing plants involves various 

 conditions of seed and flesh formation. 



2. There is some evidence that both impotence and embryo abortion 

 are also present in some degree in chicory. 



3. The experiments with chicory already reported (1916, 1917) 

 indicate (a) that self- and cross-incompatibilities are strongly in 

 evidence ; (b) that a few self-compatible plants may arise sporadically 

 from parents that are self-sterile, even after three generations of self- 

 sterile parentage ; (c) that the progeny of such self-fertile plants do not 

 breed true as to this character ; (d) that the degree of self-compatibility 

 varies; (e) and that selection for increased self-fertility after two 

 generations was not effective in isolating a completely self-fertile strain. 



4. The new data reported in this paper are fully in accord with the 

 results obtained in previous years. A new generation, the third having 

 self-fertile ancestry, exhibited quite the same irregular heredity and 

 sporadic development of self-sterility (or regression to the condition 

 of self-sterility) as was seen in the former generation. In this respect 

 every family, every line, and every series were in close agreement. 



5. Self- compatibility is entirely independent of differences in vege- 

 tative vigor. The various series of the crops grown in 1915 and 1916 

 showed widely different types in respect to vegetative vigor. Self- 

 sterility appeared in all these races with practically equal frequency. 

 Sister plants of the least vigorous dwarf race or sister plants of the 

 most vigorous vegetative race were either self-fertile or self-sterile 

 indiscriminately. 



6. Self-compatibility and self-incompatibility operate independently 

 of potential sex-vigor. The total production of flowers varied greatly 

 among the various series. Plants with large numbers of sex organs 

 were either self-sterile or self-fertile, as were plants with the fewest 

 number. 



7. Self-compatibility and self-incompatibility operate independently 

 of the purely nutritive relations Of the embryos to their parent plants. 



