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AMERICAN JOURNAL OF BOTANY 



[Vol. 9 



in water solution at the rate of 100 pounds to the acre. On August 9 the 

 plants were placed out of doors to be inoculated. The experiment was con- 

 cluded on August 27. Figures I and 2, Plate XI, illustrate the growth 

 differences obtained between the plants of the different groups in these 

 experiments. 



In table 9, the groups are arranged in order of the vigor of growth ex- 

 hibited by the plants. 



TABLE 9 



Experiment V 



This was a duplicate of Experiment IV, started a week later. The seed 

 was sown July 17, the plants were placed out of doors to be inoculated 

 August 10, and the experiment was concluded August 31. The results are 

 shown in table 10. 



TABLE 10 



Relation between Host Vigor and Pustule Size 



In all five of the soil-culture experiments there was evident a marked 

 decrease in the size of the rust pustules on the host plants the growth rate 

 of which was depressed. The lengths of 100 contiguous pustules on plants 

 from groups a and c of experiment I; groups a and c of experiment II; 

 groups a and d of experiment III; groups A and F of experiment IV; and 

 groups A and F of experiment V were found to fall into the following 

 classes ; 



