S. F. AUMSTRONG 73 



Thirty-one cultures gave clear evidence of .segregation, thougli only 

 nine of these actually contained any rust-free plants at maturity. 

 Details of rust attack on each plant in '2i of these cultures are given in 

 Table VI. It will be noted that the extent of "'disturbance of resistance" 

 varied considerably fi'oni culture to culture. In the first four given in 

 this table, it was practically non-existent; in the next four it was ap2)reci- 

 able, while in most of the others it was very great. Nevertheless, the 

 very wide difference between the nature of the attack in the extreme 

 grades, and the proportion of cases of intermediate attack, indicated 

 that JVIeudehan segregation had occurred in all these cultures. 



Table VI. Results of analysis of the F.^ ciiliures (1919) raised from F., 

 plants which had a moderate rust attack in 1918. //; this tabic are 

 grouped 24 cultures which gave clear evidence <f segregation. 



Extent of the rust attack at final examination 



250 1109 



(339-7) (1019-3) 



In addition to tlie above, seven otlier cultures gave clear evidence of segregation, but 

 full records of rust on each plant were not made. 



Most of the remaining 18 cultures had suffered very severely from 

 drought. In these segregation was much less evident, the attack varying 

 from a moderate to a veiy severe one. They were, however, distinctly 



