334 



The Journal of Heredity 



BEFORE AND AFTER DEPOLLINATION 



Figure 26. Two Crepis florets greatly enlarged, showing the effect of the water depol- 

 lination process. 



Fruwirth in the 

 Cichoriiiin Iiifybits. 



common chicory, 



Weather conditions may cause a va- 

 riation in the time of these periods of 

 anthesis activity. They are more clearly 

 defined during clear sunny days than 

 during cloudy days. Opening of the 

 fiorets takes place during the forenoon 

 and fifteen to twenty florets (those 

 of the outer whorl) develop first, while 

 the remaining inner florets show no ac- 

 tivity. Hence with the improved water 

 depollination method the pollen can be 

 washed from the stigmas of the outer 

 whorl of florets before the stiy:matic 



surface is exposed. The central florets, 

 which have not yet begun to open are 

 then pulled out. From one to three days 

 later pollen may be applied to the ex- 

 posed stigmatic surfaces of the de- 

 ])ollinated florets and the heads enclosed 

 in a paper bag. Usually, however, the 

 head is again pollinated on the two 

 succeeding days to insure fertilization. 

 This method has given satisfactory 

 results. 



Another method used for the most 

 critical hybridization work is the actual 

 removal of the undehisced stamen tube 

 from the unopen floret. This operation 

 is performed under a binocular magni- 



