12 BULLETIN" 844, U. S. DEPARTMENT OF AGRICULTURE. 



As insects, and especially honeybees, usually visit all recently 

 opened flowers on a raceme, experiments C and D were conducted to 

 determine whether more seed would be produced when pollen from 

 other flowers on the same raceme was placed on the stigmas of the 

 flowers than when only the pollen produced by each flower was placed 

 on its own stigma. The effect of pollination when only the pollen 

 produced by an individual flower was placed on its own stigmas was 

 also obtained in experiment F, as by this method of pollination no 

 pollen was transferred from one flower to another. It can not be 

 stated definitely that the seed produced by the cross-pollinated 

 flowers was the result of fertilization with foreign pollen, as the 

 anthers were not removed from the flowers pollinated because it 

 would be necessary to remove the anthers when the flowers were not 

 more than two-thirds mature, and in doing this the flowers would be 

 so mutilated that only occasionally would pollination at this time 

 or at a later date be effective. The flowers listed in experiment E 

 were pollinated a short time before they opened, and in each case 

 pollen taken from flowers of other plants was placed on the stigmas. 

 The petals of the cross-pollinated flowers were not mutilated, and 

 in each case they returned to their original positions soon after polli- 

 nation. The results obtained in experiment B, where the racemes 

 Were simply labeled and left open to the action of insects at all times, 

 serve for comparison with other experiments where the flowers were 

 protected from insect visitation and were artificially manipulated. 



Martin (25) found the setting of alfalfa seed and Westgate (40) 

 found the setting of red-clover seed to be affected by an excessive 

 quantity of moisture in the soil or atmosphere. In order to over- 

 come the possible effect of this or of other detrimental factors, in 

 each experiment only the flowers on a certain number of racemes 

 were pollinated at one time. All of the experiments were repeated a 

 number of times during the months of July and August, 1916, and 

 the results given in Table III show the total number of flowers polli- 

 nated and the number of pods that formed during the two months. 



The results presented in Table III show that flowers fertilized 

 with pollen transferred from another plant produced a higher per- 

 centage of pods than any of the other treatments. The results ob- 

 tained in experiment D, where the same toothpick was used to 

 spring the keels of all the flowers on a raceme, show that this method 

 of pollination produced an average of 7.24 pods per raceme more than 

 the racemes in experiment C, where a separate toothpick was used 

 for each flower. These results indicate that pollen transferred from 

 one flower to another on the same raceme is more effective than when 

 the pollen produced by an individual flower is used to fertilize its 

 own stigma. However, the results of experiment C prove that self- 

 pollination is effective in Melilotus alba. In experiment B, which 



