52 



Scientific Proceedings (88). 



cussion of literature and theories have already been made. A 

 brief summary of results and conclusions can be made here, 

 however, as follows: 



1. The results obtained with chicory indicate (a) that self- 

 and cross-incompatibilities are strongly in evidence in this species; 

 (b) that self-compatible plants may arise sporadically from parents 

 that are self-sterile even after three generations of self-incompatible 

 ancestry; (c) that the progeny of such plants do not breed true to 

 this character; (d) that the degree of self-compatibility varies 

 greatly; (e) that selection for high degrees of self-fertility con- 

 tinued for four generations has not been effective in isolating a 

 completely self-fertile strain. 



2. Self-compatibility and self-incompatibility are entirely inde- 

 pendent of differences in vegetative vigor. In the selection experi- 

 ments, races widely different in vegetative vigor have been 

 isolated. Self-sterility and self-fertility appeared in all these races 

 with much the same 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. 



3. Self-compatibility and self-incompatibility operate inde- 

 pendently of potential sex vigor. The total production of flowers 

 varied greatly among the various strains. Plants producing large 

 numbers of sex organs were either self-sterile or self-fertile, as 

 were plants with the fewest number. 



4. Self-compatibility and self-incompatibility may operate 

 independently of the purely nutritive relations of the embryos to 

 their parent plants. Ten flower-heads self-pollinated on a com- 

 pletely self-sterile plant will set no seed, while ten heads on the 

 same plant pollinated on the same day with pollen from a highly 

 cross-compatible plant will set abundant seed. The fruits are 

 rather small achenes having no endosperm and are practically 

 composed only of the embryo: provided the pollination is com- 

 patible, they seem to develop equally well throughout the season. 



5. Self-compatibility and self-incompatibility appear inde- 

 pendently of any combination of germ-plasm elements in so far as 

 these can be judged by the expression of characters. Each 

 operates alike between gametes that are similar or those that are 

 dissimilar in respect to hereditary units of genetic analysis. Plants 



