350 
Journal of Agricultural Research 
Vd. V, No. 8 
According to Kelley, the action of manganese, especially if present in 
the soil in relatively large quantities, 2.34 to 9.74 per cent, produces 
very radical changes in the nutrition of the plant (5). But such quan¬ 
tities of manganese as correspond to these percentages are not often 
found in soils. 
Brenchley (2, p. 583) sums up her observations on the effects of manga¬ 
nese on barley thus: 
Manganese sulfate, though not an actual toxic to barley, retards the growth very 
considerably if supplied in moderate quantities. Minute traces of the salt have a 
decided stimulative action both on the root and shoot. * * * When supplied in 
sufficient concentration manganese is taken up by the plant and deposited in the 
lower leaves. 
Jost (4, p. 87), in treating of the nonessential ash constituents ab¬ 
sorbed from the soil by plants, says of silica: 
Although silica may be quite superfluous from the chemical point of view, it may 
be of great service to the plant in the biological sense. Our knowledge of these sub¬ 
jects, despite the amount of work which has been expended on them, is still very 
imperfect, and it is possible to defend the assertion that all the ash constituents have 
definite functions to perform, although these have not as yet been determined in all 
cases, and although these constituents can not be considered as taking part in meta¬ 
bolic changes. * * * The occurrence of manganese may, however, be specially 
noted, as leading to the consideration of a new series of phenomena. It is not widely 
distributed in the earth, and yet is found, though only in traces, in very many plants. 
In discussing nutritive and stimulative materials he uses the follow¬ 
ing language concerning iron (4, p. 88): 
This distinction is not readily made out in all cases; iron, for example, is a difficult 
element to deal with, because it is essential only in the minutest traces, and is possi¬ 
bly both a nutrient and a stimulant. 
Iron is definitely recognized as essential for the growth of plants, 
though the quantities required are exceedingly small. 
The presence of manganese in wheat straw has been mentioned by 
others, but nowhere have I found its quantity given, and it is not men- 
. tioned in connection with the grain. The statement of M. Bertrand (1) 
that “manganese has been found in many grains” 1 is the only one 
known to me that may indicate the occurrence of this element in the 
wheat kernel. 
In examining the mineral constituents of wheat {Triticum spp.) I was 
struck by the fact that there w r as uniformly enough manganese present 
to come down with the calcic oxalate and to impart a decided brown 
color to the calcic oxid when ignited. A few preliminary determinations 
revealed the fact that there was as much or more manganese than iron 
present. At the time this observation was made I had examined 25 
samples of wheat and had found manganese present in every sample. 
These samples had been grown on the same soil, though the different 
plots had not received the same fertilization. The supply of manganese 
1 Author's translation. 
