III. Effect of Manganese Compounds on Certain of the Lower Plants.
The information on this point is exceedingly meagre, possibly because of the diversion of general attention to the higher plants in view of the commercial interests involved.
[Richards (1897)] carried out experiments with various nutritive media with the addition of certain metallic salts, including those of zinc, iron, aluminium and manganese. The fungi tested were Aspergillus niger, Penicillium glaucum and Botrytis cinerea. His general conclusion was that fungi may be stimulated, though it must not be concluded without further investigation that all fungi react in the same degree to the same reagent, but this conclusion is traversed by [Loew and Sawa (1902)]. These writers state that fungi are not stimulated by manganese, and take this as a proof that the improvement in the growth of phanerogams, induced by manganese compounds, is not due to direct stimulation of the protoplasmic activity, but to some other more obscure cause.