126 BOTANICAL GAZETTE [FEBRUARY 
highly self-compatible. Two series were grown from parents that 
were self-incompatible. In one of these all of the 19 progeny were 
self-incompatible; in the other series of 34 plants 27 were fully 
self-incompatible, 5 were feebly self-compatible, and 2 were self- 
compatible of medium grade during the period of mid-bloom. 
SumMARY.—The results obtained in these various pedigreed 
cultures show that self-compatibility is a character which is not 
directly hereditary. Self-compatibility occurs sporadically in a few 
members of these prevailing self-incompatible species. This 
character does not breed true. Selection for self-compatibility 
does not immediately lead to the establishment of self-compatible 
races. Neither is self-compatibility nor self-incompatibility domi- 
nant in crosses. There is some indication, however, that certain 
races may be secured in which the mode of distribution in respect 
to self-compatibility is higher than in others. 
Discussion and conclusion 
The strains of Brassica pekinensis and B. chinensis studied 
were previously selected and bred for excessive leafy growth rather 
than for fruit and seed production, yet they are reproduced exclu- 
sively by seeds. The vegetative vigor is not in the least utilized 
in the development of parts which may propagate the plants 
vegetatively. In their habit of growth and bloom, the stage of 
sexual reproduction in these plants quickly follows a period of 
remarkably vigorous vegetative development, hence these species 
are favorable material in which to study the correlative relations 
of the asexual or the vegetative phase to the sexual or reproductive 
(by seeds) phase in the complete life cycle. 
The two types of sterility, impotence (including flower abortion 
and arrested development), and proliferation, or the destruction 
of a pistil by vegetative growth, as they occur in B. pekinensis and 
B. chinensis, are both phenomena associated with the formation 
of floral organs. The other type of sterility, physiological incom- 
patibility or relative sterility which is present, is concerned with 
the physiological inter-relations of the sex organs in the various 
processes of fertilization. 
These three types of sterility develop and operate in these two 
species and in their hybrids in intimate correlation with the cyclic 
