alfalfa flowers. ?/ind, as a possilDle agency that might 

 have caused the flowers to he tripped during this period, 

 should, evidently be eliminated. 



During the period from August 22 to August 26, 

 several hours were spent in the alfalfa fields each day; 

 during this time not a single wild or domestic honeyhee, 

 or a hum'ble'bee was seen. In the more favorable weather 

 conditions that existed during the three or four days 

 preceding about five or six wild bees of the genus 

 Megechile were observed flying about the fields. Ho 

 domestic honeybees were seen. The horsey gathering insects 

 that were present in the large fields of alfalfa, were 

 present in such limited numbers that not more than a very 

 small percentage of the flowers that were tripped during 

 this period, could have been tripped by these insects. 



It was clearly demonstrated at Chinook, Montana, in 

 1909, and at Pullman, ¥ash., in 1910, that alfalfa flowers 

 do become automatically tripped under certain conditions. 



The most plausible explanation for the fact that 

 during the period immediately preceding August 22, nearly 

 all of the alfalfa flowers in these two fields became 

 tripped and developed into pods, while during an earlier 

 period but few pods were produced, and during the period 

 subsequent to August 22 practically no flowers became 

 tripped, seems to be that Just prior to August 22 condi- 

 tions were favorable for alfalfa flowers to become 



(39) 



