POLLEN AND PISTILS OP APPLES 407 



remains viable much longer than poUen exposed to variations in 

 moisture. Tokugawa (22) kept some pollen of four species of 

 plants stored under unifoimily dry conditions and some stored 

 in a room where it was exposed to the fluctuating moisture con- 

 tent of the air. The pollen in constant dryness retained its vi- 

 tality from 31 to 98 days while that stored in the room retained 

 its vitality only from 9 to 24 days. Molisjh (16) found the 

 longevity in storage to range from 12 to 72 days in a number of 

 plants which he investigated. In the grasses Jost (7) found the 

 longevity to range from 1 to 8 days. 



Sandsten (19) ohtained some germination in apple pollen 

 after a storage of six months. Adams (1) <j'btained germina- 

 tion after a storage of three months. Lewis and Vincent (11) 

 found apple pollen to be effective after a storage of three weeks 

 in vials plugged with cotton. Crandall (4) found that apple 



pollen which had been stored more thau 11 days did not give 

 satisfactory results in pollination experiments. In our work, 

 the pollen of flowers kept in .paper bags on a table in the labora- 

 tory, gave no germination after a storage of 18 days. 



Observations and statistics show that the weather conditions 

 at the time of pollination have an important influence on the 

 setting of fruit. Hedrick (6) concluded from statistics rang- 

 ing over a period of twenty-five years, that rain and the accom' 

 panying cold and wind cause the loss of more fruit than any 

 other climatic factor. In his opinion there are several ways in 

 which wet, cold weather interferes with the setting of fruit. 

 One is that the stigmatic secretion, which he thinks is very much 

 essential to the proper germination of the poUen, is either 

 washed away or so diluted that the pollen does not germinate. 

 His statistics show that bright, warm, dry weather at the time of 

 blossoming is the most favorable for good crops of fruit. He 

 adds that under these conditions there is more and better pollen 

 produced, and that the stigmas show a greater amount of secre- 

 tion. On bright, warm days, we found no evidence of any secre- 

 tion on the surface of the stigmas in the five varieties of apples 

 investigated. The poUen germinated when lodged between the 

 papillae in the absence of any secretion. It was found that im- 

 mersing in water and low temperatures retarded the germina- 

 tion of the poillen. If the weather is cold and wet at the time of 

 blossoming, both the presence of water on the stigmas and a low 

 temperature may interfere with the proper functioning of the 



