THE FUNCTION OF MANGANESE IN PLANTS 
W. PP, Kertiry 
Historical introduction 
Dating from the time of ScHEELE (1), numerous investigators 
have noted the presence of manganese in plants of various orders. 
While small amounts only of this element have been found in most 
plants, in 1860 Hizcarp (2) pointed out that the ash of the long- 
leaf pine from Mississippi contains a relatively high percentage; 
and in 1878 J. ScHROEDER (3) found in the ash of the Norway 
spruce (Picea excelsa) 35.53 per cent Mn,O,, and in the ash of 
the bark 41.23 per cent. These and other observations, however, 
received but little attention for many years. Manganese occurs 
in small amounts in practically all soils, but being an element 
unessential to growth and normal development, its absorption by 
Plants was considered to be without physiological significance. 
The discovery of BERTRAND (4) in 1897 of the occurrence of 
Manganese in the oxidizing enzymes of plants, however, and the 
Subsequent finding that small amounts of manganese salts stimu- 
late the oxygen-carrying power of these catalytic agents, have 
drawn attention to this question and have led to the view that after 
all a physiological réle is probably played by this element. Since 
the time of these discoveries a large number of experiments, with 
4 wide range ‘of plants, have been made, various compounds of 
Manganese in water and soil cultures being used; and, in general, 
it has been found that small amounts of manganese bring about 
stimulation in growth. While small amounts often produce stimu- 
ation, wherever more than a very low concentration has been 
employed, toxicity has resulted. 
Loew (5) and his co-workers in Japan found, furthermore, the 
toxic concentration in water cultures to be different for different 
*Pecies of plants. A concentration that was stimulating to rice, 
for mstance, proved to be toxic to barley. Likewise, SALOMONE 
(6) observed in field experiments that the application of such small 
amounts as 40 kilograms per hectar of manganous sulphate pro- 
213] [Botanical Gazette, vol. 57 
