SWEET-CLOVER SEED. 



11 



cms plants growing on well-drained soil were selected for these ex- 

 periments. Before any of the flowers were open, the individual 

 racemes were covered with tarlatan and labeled. (Fig. 5.) As soon 

 as part of the flowers opened, the racemes were uncovered and after 

 removing all flowers that were not open the open flowers were polli- 

 nated and the racemes re-covered. If the flowers of sweet clover 

 'are not fertilized they will remain open for two to three days, then 

 wither, and in a short time drop. But after being fertilized the ovules 



Fig. 5.— Individual racemes of white sweet clover covered with cheesecloth to protect them from insect 



visitation. 



enlarge very rapidly, and the corollas usually drop in about seven 

 or eight days. Therefore, all fertilized flowers can be distinguished 

 a few days after fertilization has taken place. Counts were made of 

 the number of pods which formed in 10 to 12 days after pollination. 

 An outline of the experiments is given in Table II. 



Table II. — Treatment of sweet-clover flowers in the artificial-manipulation experiments. 



Experiment. 



A, 

 B 

 C 

 D 

 E 

 F. 



Method of pollinating the flowers. 



Check— covered. 



Check— open to insect visitation at all times. 



A separate toothpick was used to spring the keel of each flower on the raceme. 



One toothpick was used to spring the keels of all the flowers on a raceme. 



Cross-pollinated. 



Raceme rolled several times between thumb and finger. 



