176 BOTANICAL GAZETTE [SEPTEMBER 
that there is a tendency for the area of greatest growth under these 
conditions to be nearer this end. 
In other words, when dihydroxystearic acid is present the results 
show a tendency for the ratios of the materials removed from the 
solution to fall nearer to the nitrogen end of the diagram than they 
do in the case of cultures where this substance_is absent. This 
P05 ~ 
Fic. 9.—Showing the ratio of the original, the final, and the ratio of the loss of 
P.0;, NH;, and K,O from the culture solution, in the first period. 
tendency is marked from the very first, as is shown by the diagram 
given in fig. 9 for the first period. Moreover, the points, for 
instance, of the ro per cent mixture of P.O, lie very low, and this 
tendency to lie lower than in the cultures which contained 1° 
dihydroxystearic acid is found throughout the experiment, though 
it is not equally marked in all periods. The average effect has. 
already been given in the diagram fig. 8. The strong tendency 
