358 University of California Publications in Agricultural Sciences [Vol. 1 



concentration in this series is not so marked as in series I, but 

 is slightly evidenced in the somewhat better growth of some of 

 the plants in groups C and D as compared with plants in groups 

 A and D (pi. 9). The height of the plants at two different 

 periods in llicir growth was taken in this series at the same time 

 that the measurements were taken in series I and plotted against 

 total concentration (fig. 6). The total concentration of salts in 

 the solution is here, as in series I, of secondary importance when 

 one element is present in insufficient amount, as will be seen 

 (pi. 6) when plant II C 1 (3.20 g.) is compared with II C 3 



Decigrams. 

 Dry wt. of tops 

 100 



Ca(HoP0,)2 



Fig. 7. — Graph showing the influence on dry weight of tops of equal 

 quantities of CaCH.PO^), in the different groups of series II. 



(3.38 g.). While the total concentration is practically the same 

 and the total quantity of each of the other salts is the same the 

 Ca(HoPOJ., in II C 3 is ten times the quantity of the same salt 

 in II C 1. 



Dry Weight in Series II 

 A comparison of height (tig. 5) and dry weight curves (fig. 7) 

 for tops in this series shows that height here is not an accurate 

 index to dry weight. Thus group A gave the greatest total dry 

 weight, while the greatest total height of plants occurred in 

 group D, a fact which is explicable since very serious injury 

 resulting in a spindly habit was shown by many plants in the 

 D group, as will be pointed out later in the discussion of injury 

 due to the improper balance of salts in the solution. 



