Feb, i6, 1920 



Germination of Barley Pollen 



529 



hybridization are due much more to faulty pollen than to any lack of 

 receptivity of the stigma. 



The viability of the pollen was tested both in 191 7 and in 191 8. As in 

 the laboiatory, the results were inconsistent, the variations indicating 

 the readiness with which the viability of the pollen is affected. Forty 

 flowers were used as a unit, as before, and all pollinations were made 48 

 hours after emasculation. In 191 7, a different variety was selected for 

 the test than was used in the experiment on receptivity of the stigma. 

 Owing to the more advanced stage of the development of the plants, 

 pollen was more difficult to obtain, and the highest percentage of success- 

 ful pollinations was lower than in the previous experiment. The results 

 are shown in figure 2. 



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FiG- 2. — Number and percentage of seed produced by the use of pollen from anthers at various stages of 

 development before and after dehiscence. 



Anthers in eight different stages of development were used. In the 

 first of these the anthers were green in color. In the second the anthers 

 were yellow in color but did not yield dry pollen when broken. In the 

 third the anthers were yellow in color, and pollen was secured from them 

 only with difficulty. In the fourth stage the anthers were ready to break 

 and yielded abundant dry pollen when ruptured. In the fifth stage the 



