374 E. P. DEeaTRICK 
of the oxidase, so far as the activation and transfer of oxygen is con- 
cerned, whereas the acid albuminoid radicle would impart to the ferment 
its other properties, such as its conduct toward heat, solubility, ete.” 
Manganese has been found to activate animal ferments. Considerable 
work has been done on the oxidizing power of colloidal solutions of 
manganese, which are described by Kastle as artificial ferments. 
The reports of numerous investigators indicate that a relation exists 
between the presence of manganese and the production of chlorophyll. 
Van Dam (1907) states that seeds soaked in a solution of manganese 
sulfate yield plants which develop greener leaves than normally. Jadin 
and Astruc (1912) report that manganese constantly occurs in the ash 
of plants and that the chlorophyll-bearing parts contain the greatest 
proportion of this element. Mameli (1912) found that chlorophyll is 
produced in some of the lower plants only when manganese is added 
to the nutrient media. Pugliese (1913) states that there is an optimum 
ratio for iron and manganese, which he gives as 1:2.5. Mazé (1914) 
has described a special type of chlorosis due to the lack of manganese; 
a large amount in the plant also causes chlorosis. Gile (1916) is of the 
opinion that ‘‘ manganese chlorosis may be due in part to a deficiency of 
iron in the plant, induced by the action of manganese in the plant or 
in the soil, and in part to a direct toxic action of the manganese.”’ Johnson 
(1917) finds that the toxic effect of manganese on pineapples appears 
to be “‘ due to a depression in the assimilation of iron,” and has worked 
out a commercially successful method of counteracting the toxic effect 
by supplying iron thru the leaves. 
Experiments with soil cultures 
A large number of experiments are reported in which manganese salts 
have been applied to soil as a fertilizer. The results are somewhat con- 
tradictory. 
Von Feilitzen (1907) found that manganese sulfate did not increase 
the yield of oats perceptibly. Pfeiffer and Blanck (1912), after experi- 
menting with various salts and plants, decided that their results were 
not conclusive. They state that, while increased yields were occasionally 
obtained, the salts of manganese should not be recommended for general 
use as a fertilizer. This opinion is held also by Sullivan and Robinson 
(1913), who advised that manganese should not be used “in any way 
