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 



certain other relations. 



A total of 13 7 1 plants of 

 these two species of Brassica 

 and hybrids between them have 

 been tested at the time this is 



Fig. 4. — Plant of B. pckincnsis, com- 

 pletely self-incompatible but producing 

 good pods containing viable seeds to com- 

 patible crosses at any time while flowers are 

 fully developed. 



Fig. 5. — Feebly self-compatible plant 

 of B. chinensis; first two flowers and 

 last to open normally on main axis highly 

 fertile in compatible cross. 



written, and of these 653 were found to be completely self- 

 incompatible. 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 



