120 BOTANICAL GAZETTE [FEBRUARY 
numerous plants with results as noted, which show that the failure 
to set seed to self-pollination is due to a sexual incompatibility 
between reproductive elements that are capable of functioning in 
Fic. 4.—Plant of B. pekinensis, com- 
pletely i eeccsraithe but producing 
good pods containing viable seeds to com- 
patible crosses at any time while flowers are 
fully developed. 
written, and of these 653 were 
incompatible. 
certain other relations. 
A total of 1371 plants of 
these two species of Brassica 
and hybrids between them have 
been tested at the time this is 
et 
= 
ae 
Be 
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Fic. 5.—Feebly self-compatible plant 
of B. chinensis; first two flower rs and 
Ske N hiv 
avic hic’ 
fertile in compatible cross. 
found to be completely self- 
Plants were thus classed when no pods developed 
to selfing at any time throughout the entire period of bloom. 
There were, however, several grades to be seen in respect to the 
length of time the pistils remained attached to the plant. In the 
plant shown in fig. 4, with few exceptions, the pistils of flowers 
