1917] Ay res: Nutrient Solution on Plants Grown in Sand Cultures 347 



to group D in each series. The third important variant, the 

 balance of salts in the solution, follows as a matter of necessity, 

 since the single nutrient salt added in increasing quantities from 

 plant 1 to plant 5 is added with uniform variation and in the same 

 quantity in each group, while the quantities of the other salts, 

 although constant within a group, are not constant within all 



TABLE 1 



Weight in Grams of Salts Addkd to Each Pot Containing 2000 Grams 



OF Sand 



(In the following table the roinan numerals indicate the series numbers, 

 and the letters are those of the corresponding groups.) 



