No. 553] VARIATION IN CORN AND BEANS 



63 



though nitrogen did have this effect. Nitrogen together with 

 cither phosphorus or potash had a more pronounced effect, and 

 when all three were applied together in plot 11 the stature was 

 still greater. Increasing the amounts of the commercial fertil- 

 izers and adding manure in plot 12 gave still taller corn. 



The standard deviation is apparently increased by the mineral 

 elements either alone or together, while nitrogen operates to 

 lessen this measure of variability. When all are used together 

 both influences seem to operate and the standard deviation is 

 increased, but not so much as with the mineral elements alone. 

 The increase of the standard deviation where considerable 

 amounts of complete fertilizer is added is not in proportion to 

 the increased mean, and the coefficient of variability is lessened. 



It was not found possible to make any measurements bearing 

 on the vegetative vigor of the bean plants: the only figures avail- 

 able are those of yield as measured by the total number of pods 

 on each plant. Table III indicates that potash was most effec- 

 tive in increasing the mean number of pods per vine, though it 

 will be remembered that this element was of the least avail with 

 corn. Nitrogen seems next, and there is a possible beneficial 



consistent as in the case of stalk height of corn. This variability 

 in yield finds further expression in the larger variation within 

 each plot as expressed by the coefficients of variability which 

 are nearly three times as great as those for stalk height of corn. 

 The effect of the single elements on the standard deviation is 



