1922] STOUT—STERILITY 123 
plants, the flowers that opened normally during the time of self- 
incompatibility were functional in compatible crosses. The re- 
sults of a test of this sort are shown in fig. 5. The cyclic develop- 
ment of self-compatibility with its coordination among the various 
branches of an individual according to time of bloom is shown in 
figs. 2 and 3. 
There is evidence from other species (StrKs 10) that various 
grades of cross-compatibility may exist between the individuals of 
the same race or species, that the group relations may be variable 
in different cultures of the same species or race (East and Park 4), 
and that in general cross-incompatibilities appear with much 
the same irregularity in heredity and in expression as do self- 
incompatibilities. 
The writer’s studies with these plants have been chiefly con- 
cerned with self-compatibility. In the species of Brassica studied 
the cross-relations have not been studied sufficiently to state with 
certainty whether the grades of cross-incompatibility undergo 
cyclic changes like those of self-incompatibility, but perhaps it 
may be assumed that certain of the weaker grades of. cross- 
incompatibility do thus operate. 
Heredity of mid-bloom self-compatibility in pedigreed 
lines of descent 
In the first or ‘‘parent”’ series grown of both Brassica pekinensis 
and B. chinensis, of a total of 253 plants there were 21 plants that 
produced viable seeds to self-pollination during the period of 
mid-bloom. From such seeds pedigreed progenies were grown 
through two generations, to test the inheritance of self-compatibility 
and to determine the result of repeated selection for this character. 
A summary of the records for the various series and families grown 
to date is presented in table I. In these records the first series of 
plants grown are given arbitrary numbers. The number of a series 
with that of the self-compatible plant used as a seed parent is 
employed in designating the series of succeeding generations. 
Thus the line of descent and the relationship of the various series 
of sister plants are fully indicated. 
In one series of the selfed F, generation of B. pekinensis (series 
1-2) comprising 88 plants, 24 were strongly self-compatible. In 
