24 ABSORPTION AND EXCRETION OF SALTS BY ROOTS. 
These results indicate (1) that in solutions (Nos. 2-12) 10 times as 
concentrated as solutions near equilibrium concentration (Nos. 1 
and 13), amagnesium to calcium ratio of : is as favorable to absorp- 
tion as calcium alone; and (2) that the most efficient absorption takes 
place from solutions with magnesium and calcium present in approxi- 
mately equivalent concentrations, i. e., in the ratio 2. Since in this 
Sy 
179. Ge 2 ; 
As A 
Be 
Ca ( v (Ozd2- 
zy sp 
Fic. 12.—Seedlings of culture 3, experiment 3, 
experiment the solutions of equivalent concentration were 10 times 
as dilute as in experiments A and B, it is interesting to note that the 
same ratio of magnesium to calcium as in those experiments sufficed to 
bring about perfect root development. In the figures illustrating the 
more significant cultures of this series note especially the contrast 
10 M 9M M pc, (gst 
between the effects of 50 50,0008 and 50 50,0008 + 50,000 
and 12; cf. figs. 1 and 8); the general similarity of cultures in ao a 
231 
ao 
