conducted, did not have any effect except "by excluding 

 insects, upon the development of the flowers under it. 

 In 1908, flowers on a numher of different alfalfa 

 plants were enclosed in netting; a portion of the flowers 

 had "been naturally tripped "before they were enclosed in 

 netting, while other flowers had not "been tripped. Of the 

 flowers which were tripped "before insects were excluded, 

 58 percent produced seed. Of the flowers which were not 

 tripped at the tiqje insects were excluded, 5.2 percent 

 produced seed. The pods developing from the flowers which 

 had "been tripped contained 3.53 seeds each, while the pods 

 developing from the flowers which were not tripped when 

 enclosed in netting contained 1 seed each. The results 

 of this experiment agree su"bstantially with the results of 

 other series of experiments, in showing that at Pullman, 

 Wash,, pods and seed ordinarily develop in large numbers 

 only when the flowers have "been tripped "by insects or some 

 other agency; "but that even when insects have "been excluded 

 a comparatively small percentage of the flowers produce 

 seed. The results of this experiment also indicate that 

 a larger num"ber of seeds per pod develop when the flowers 

 have "been tripped "by insects, than when the flowers have 

 "been tripped under conditions where there is not an oppor- 

 tunity for the flowers to "become fertilized with pollen 

 from other plants. 



(54) 



