226 BOTANICAL GAZETTE [MARCH 
he found the protoplasm to undergo visible changes, which, how- 
ever, were not necessarily injurious to it. Protoplasm, being of a 
colloidal nature, then, becomes physico-chemically altered when — 
placed in certain solutions; and such alterations, in turn, affect 
its permeability. 
By the application of the above named conceptions, we may 
infer that when plants are grown on manganese soils, the soluble 
manganese, coming into contact with the root hairs, is at first 
absorbed, up to a certain point, forming combinations with the 
protoplasm. Once these combinations are established, the per- 
meability of the protoplasm becomes altered, whereby the absorp- 
tion of lime is facilitated, while that of magnesium is hindered. 
Manganese, then, may be looked upon as forming a combination 
with the protoplasm which materially alters the relative absorp- 
tion of lime and magnesia. Not all plants are equally affected by 
a variation from the normal ratio of lime to magnesia, and there- 
fore under field conditions toxic effects may be produced in some 
plants, stimulation in others, while with still others the effects may 
be neutral. 
The experimental facts presented in this paper and the inter- 
pretations made in no way negative the work previously done on 
this subject. The failure to observe a more active catalytic oxt- 
dizing reaction in plants from highly manganiferous soil does not 
argue that manganese is incapable of stimulating the activity of 
oxidizing enzymes. The normal soils of Oahu, from which plants 
were taken for comparison, contain small amounts of manganese, 
which, moreover, was found to be absorbed to a considerable extent 
by all the plants studied. It is probable, therefore, that the absorp- 
tion of manganese from the normal soils of the Islands is sufficient 
to produce maximum stimulation in oxidase activity. 
Hawatt EXPERIMENT STATION 
ONOLULU 
LITERATURE CITED 
1. SCHEELE, Kart W., Memoires de Chymie. Dijon. ee 
2. HItGArRD, E. W., Renoct of Geol. and Agr., Miss. p. 360. 1 : 
3- SCHROEDER, J., Untersuchen iiber Forstchem. und Palansenphysil 
Tharand. Forstl. Jahrb. Supp. 1:97. 1878. 
