468 
AMERICAN JOURNAL OF BOTANY 
[Vol. 9. 
2. Zinc has a stimulating effect in the case of a limited number of 
organisms. In the case of some 15 species of parasitic organisms, zinc did 
not accelerate growth. 
/ 
/ 
/ X 
ZHO3 
-7 - 
X 
1 
2 \ 
\ 
\ 
\ 
5 \ 
z 
%S04 
X 
X 
X 
Ca(H2P04)2 
Pig. 3. 
Macro sporimn sarcinaef orme, 
/ 6 \ 
X ^ 
/ 2 
/ X 
4 ^ 
X \ 
/ 6 
7 
Ca(H2P04)2 
Fig. 4. 
Phoma apiicola. 
