Manganese Sulphate upon the Growth of Barley . 579 
manganese, Kahlbaum’s sublimed ferric chloride was used to ensure 
its purity. 
By April 8, about four weeks after the start, marked differences were 
manifest in the plants. Those growing in the strongest toxic solutions 
1 : 10,000 M.S., had very brown roots, especially near the seed, probably on 
account of some deposit of manganese. These same plants gave every 
indication of being diseased, as the lower leaves were also very brown and 
appeared to be badly infected with rust, which died out gradually towards 
the upper leaves. 
The next concentration 1 :100,000 M.S. showed very little brown 
coloration on the roots and much less discoloration of the lower leaves. At 
a weaker strength still, 1: 1,000,000 M.S. and less, the roots were strong, 
healthy, and white, while the indications of possible disease were very 
slight and died out altogether lower down the range of concentration. 
This appearance of ‘ rust ’ so early in the season was rather unexpected, 
so, as no other plants in the greenhouse seemed to be attacked, further 
investigations were made. A microscopical examination showed no signs 
of any fungal disease, but indicated that the cells were simply dead and 
brown while retaining their normal shape and size, at any rate in the early 
stages. The dead cells at first occurred in small patches which gradually 
spread and coalesced till finally the whole leaf was involved. Appearances 
pointed to death on account of manganese poisoning. Some of the affected 
leaves were detached and fused with a mixture of sodium carbonate and 
potassium nitrate. The resulting mass when dissolved in water gave a green 
coloration, indicating the presence of manganese. 
It is thus evident that the manganese is taken up by the plant roots 
and finally deposited in the cells of the leaves, which are killed if the con¬ 
centration of the salt is sufficient. Whether the manganese is further 
excreted by the leaves and deposited on the outer surface is a point that is 
not as yet cleared up. 
The plants grew steadily, one series being photographed on May 1, 
eight weeks from the beginning of the experiment (PI. XLVII, Fig. 4). After 
eleven weeks, as the food solutions were getting exhausted and unable 
to support growth, the roots were carefully washed in distilled water, and 
the plants were placed in fresh nutritive solutions with a new quota of man¬ 
ganese sulphate, the concentrations remaining the same. At this date it was 
evident that manganese was deposited in the leaves even at so low a con¬ 
centration as 1: i,ooo,oco M.S. and in some cases traces could even be 
observed in 1: 10,000,000 M.S. By June 2, after three months’ growth, most 
of the plants began to show ear, and by July 14, when the plants were 
harvested, a large proportion of the ovules had set and ripened to fully 
developed grains. 
An examination of the plants at the time of harvesting indicated that 
