feest | 
XXXII.—PRELIMINARY NOTE ON THE ABSORPTION OF 
SELENIUM BY PLANTS, sy CHARLES A. CAMERON, 
M.D. 
[Read 19th May, 1879. | 
THE subject of the possibility of replacing some of the elements 
found in plants by other elements of the same atomicity has not 
engaged the attention of British chemists; but on the Continent 
a few attempts in this direction have been made, generally with 
but little success. For example, Birner and Lucanus vainly at- 
tempted to replace ferric oxide (Fe,O,)in plants by the manganese 
analogue of that compound (M,O,;). Experiments made with the 
view of substituting sodium for potassium in plants have invari- 
ably given negative results. The possibility of completely re- 
placing an element in plants by another was, however, proved by 
me in a paper read before this Society in 1863. I found that 
rubidium was capable of taking the place of potassium. It may 
be that certain bodies, though not capable of completely replacing 
other substances in vegetables, may be partially substituted 
therefor, The varying proportions of sodium and potassium found 
in the ashes of plants would seem to indicate such a partial re- 
placement. As a rule, whenever potassium is sparely present in 
the ashes of a plant, sodium abounds therein, and vice versa. 
The analogy between sulphur and selenium suggests the possi- 
bility of the latter wholly or partly replacing the former as a 
constituent of vegetables. Sulphur exists in plants in two con- 
ditions—namely, asa constituent of sulphuric acid, and as an 
ingredient of albuminous and certain oily bodies. Sulphur is 
only taken up into the mechanisms of plants in the form of sul- 
phates, such as, for example, calcium and sodium sulphates. By 
the partial deoxidation of these sulphates sulphur is procured by 
the plant, and employed in the elaboration of its albumin, casein, 
and other albuminoids. The results of the interesting experi- 
ments of Arendt render it probable that sulphur is both oxidized 
and deoxidized in the plant at different periods of its development. 
Thus, after blossoming, the oat was found to contain more sulphur 
