POLLEN AND PISTILS OF APPLES 399 



ricultural Experiment Station, was self-pollinated and stigmas 

 examined after 48 hours. On 20 stigmas examined 118 pollen 

 grains were counted and 24 of the number had germinated, the 

 number of germinations on a stigma ranging from 2 to 6. The 

 results show that the pollen of the Jonathan can germinate on 

 its owTi stigma and if this variety is self -sterile in the orchard of 

 the Iowa State College the cause can not be attributed to the in- 

 ability of the pollen to germinate on the stigmas of the Jona- 

 than. 



THE EFFECT OF AGE AND DRYING ON THE GERMINATION OF 



THE POLLEN. 



In determining the effect of age and drying, pollen was taken 

 from buds about two days previous to opening, from flowers in 

 which the anthers were dehiscing, and from flowers which had 

 been stored in paper bags in the laboratory. The average of a 

 number of germination tests of pollen from buds and open flow- 

 ers were 75 and 87 per cent. The results show that pollen taken 

 from flowers just previous to their opening or about the time 

 the flowers are emasculated in pollinating experiments is about 

 as good as pollen from anthers which are dehiscing. The pollen 

 stored in the paper bags all died within 18 days and very little 

 was found viable after 12 days ' storage. It was also found that 

 exposure to sugar solutions in which the pollen remained plas- 

 molyzed soon resulted in death. More than 90 per cent were 

 killed when exposed to a 70 per cent cane sugar solution for 72 

 hours. 



