722 
Journal of Agricultural Research 
Vol. XXI, No. io 
of experiment I and those of the ammonium-sulphate series (B) of experi¬ 
ment II were greatly restricted in the growth rates, as already explained. 
The yields from these two series will, therefore, not be considered in rela¬ 
tion to the salt proportions of the culture solutions. 
The relative yield values as given in Table III for the six cultures pro¬ 
ducing the highest yields in each of the two scries here to be considered 
were plotted on the tetrahedral diagram like that employed by Totting- 
ham ( 18 ) but here presented in perspective in somewhat the same 
manner as was done by Espino (j). v Since the low and medium yields 
have little interest in this connection, they will be omitted from the dia¬ 
grams and discussion. The high yields of tops for both series were plotted 
Fig. 8. Distribution of relative dry-weight values of tops for the best six cultures in each series. 
on a single diagram, as were also the corresponding yields of roots for the 
two series. The areas representing the high yields of the two series are 
distinguished by shading. On the diagram of figure 8 the dotted areas 
represent the yields of tops from the best six cultures of the Tottingham 
series (series A of experiment II), and the stippled areas represent the 
corresponding yields from the best six cultures of the ammonium- 
sulphate series (series B of experiment I). The relative dry-weight yields 
of roots from the best six cultures of each of the two series are similarly 
represented on the diagrams of figure 9. 
Comparing now the areas representing the high yields of tops from the 
Nottingham series with those representing the corresponding yields from 
the ammonium-sulphate series, as shown on the diagram of figure 8, it 
