i7, 6 Trelease: Salt Requirements of Wheat Plants 581 
decrease in the partial concentration of the three salts used 
by Shive. 
A set of cultures, which may be designated as series III A, 
was conducted in order to determine whether the low top yields 
obtained with high proportions of potassium chloride were due 
to the reduction in concentration of the essential salts or to the 
high concentration of potassium chloride itself. This series was 
carried out from January 23 to February 24, 1917. The dry- 
weight data for this series are shown in Table 14. Four solu- 
tions were used in this set. The first of these was the T7R1C1 
solution, which was used in series I and II, and which, it will be 
remembered, has 0.7 of its osmotic concentration due to potas- 
sium chloride and 0.1 due to each of the other salts, monopotas- 
sium phosphate, calcium nitrate, and magnesium sulphate. This 
solution contains a very high proportion of potassium chloride. 
In both series I and series II it produced very low top yields. 
In the case of the second solution designated [T0R3iC3|- (0.48 
atmosphere)], the composition was the same as that of the 
T7R1C1 solution, except that the potassium chloride was omitted. 
The dry yield of tops produced by this solution was 0.764 gram, 
while the yield from the T7R1C1 culture was 0.700 gram. It is 
thus clear that the omission of the potassium chloride did not 
markedly increase the yield of tops. The next solution [T0R3J 
C3i (1.60 atmospheres)] was derived from the T7R1C1 solution 
by the omission of potassium chloride and the addition of suffi- 
cient amounts of the other salts to give a total concentration of 
1.60 atmospheres. It will be seen that this solution is similar 
to the second solution, but that the total concentration is here 
increased from 0.48 atmosphere to 1.60 atmospheres. The yield 
from this culture was 1.221 grams. Thus a very marked in- 
crease in yield is brought about by increasing the essential salts 
from the concentration in which they occur in the T7R1C1 solu- 
tion (0.48 atmosphere) to a total of 1.60 atmospheres. The 
fourth solution of this set (T10R0C0) was a single-salt solution 
containing potassium chloride in sufficient amount to give an 
osmotic concentration of 1.60 atmospheres. The yield from this 
culture is very low, being only 0.265 gram. From this set of 
cultures it may be concluded that the very low yields obtained 
in series I, II, and III with very high proportions of potassium 
chloride were due principally to the reductions in the amounts 
of the essential salts and not to any specific effect of the potas- 
sium chloride. 
