386 



University of California Puhlications in Botany L^^ol. 5 



however, the results serve merelj' as approximate estimate of the 

 abscission reaction time. 



In obtaining the records tabulated below a separate tag was sup- 

 plied for each flower. This tag was put on the flower at the begin- 

 ning of the observation, the plant visited twice a day thereafter and 

 records kept on the tags, which were left on the flower until the close 

 of the observation. If a flower fell upon being tapped or shaken, 

 abscission was considered to have occurred and the date was recorded 

 on the tag, which was then collected. Similarly, in the case of the 

 records for abscission of the corolla, a slight pull had to be applied 

 before it could be determined whether abscission had occurred. As a 

 means of preventing fertilization, the stigma was cut away in addi- 



TABLE 1 



^ The buds recorded here were of such size that the corolla and calyx were of the 

 same length. 



^ Sterile pollen applied to the stigma. 



* By normal flower-fall is meant fall due to lack of fertilization. 



