1917] Ay res: Nutrient Solution on Plants Grown in Sand Cultures 359 



Flower Production in Series II 

 The total number of flowers produced in this series was larger 

 than in series I, due largely to the fact that there was less stunted 

 growth in plants 1, 2, and 3 of each group, for which an ample 

 supply of nitrogen was available. Plants II A 1, II B 1, and 

 II C 1 did not produce any flowers. The greatest number of 

 flowers was formed in group C and the greatest yield of any one 

 plant was given by II B 5. The flower yield in each group is 

 definitely related to the general character of the plant as men- 

 tioned above in connection with series I. 



PHYSIOLOGICAL EFFECT OF POTASSIUM 



Distribution op Salts in Series III 



The plants in series III were grown to study the physiological 

 influence of various quantities of potassium added as K.SO4 in 

 the presence of a sufficient supply of other nutrient salts, fol- 

 lowing the same plan as outlined above for the variation of 

 nitrogen and phosphorus in series I and II. K^SO^ was present 

 in the same weight in each of the four groups A, B, C, and D, 

 the quantities added to each of the pots 1 to 5 being 0.02 g. 

 (.001 per cent), 0.1 g. (.005 per cent), 0.2 g. (.01 per cent), 1.0 g. 

 (.05 per cent), and 2.0 g. (.1 per cent). The maximum weights 

 of the other salts were NaNO,, 3 g. ; Ca(H,POJ,, 1.2 g. ; MgSO,, 

 0.96 g., in group A. In group D the minimum quantities of 

 these salts were 0.75 g., 0.3 g., and 0.24 g., respectively. The 

 total concentration in this series varied from 1.31 g. to 7.16 g. 



Height in Series III 

 No plants in this series were less than 50 cm. high, due to 

 the fact that the two nutrient elements, nitrogen and phosphorus, 

 which in the order named are of first importance as growth 

 factors, were present in sufficient quantitj^ to insure considerable 

 growth (pi. 7). Only a small quantity of K,SO, (.005 to .01 

 per cent) was required in this series to give plants of maximum 

 height, hence the curves show a downward trend in all plants 

 after either plant 2 or plant 3 in each group (fig. 8, also pi. 12). 

 Thus it is evident that there is a toxic effect of an excess of 

 potassium, irrespective of the total concentration of the solution. 



