462 
coloring matter, a volatile balsamic substance, and certain salts. The 
greater part of the valuable constituents are extracted by dilute 
alcohol. , 
FORMATION OF CARBO-HYDRATES IN PLANTS.—An important con- 
tribution to our knowledge of the formation of the carbo-hydrates in 
plants has lately been made by Herr A. Stutzer, of GOttingen, in a 
paper presented to the Chemische Gesellschaft zu Berlin. 
The views held by leading authorities on the subject vary so materi- 
ally that the author was led to make a series of culture-experiments in 
order to test them. Liebig and Rochleder hold that the organic acids 
(oxalic, tartaric, &c.) form the transition-links between atmospheric 
carbonic acid and the carbo-hydrates ; while other authorities, such as 
Davy, Sachs, &c., hold totally different views, believing that they are 
formed directly without intermediate steps. For testing the views of 
Liebig, he experimented with young plants of Brassica rapa, which are 
distinguished for their moderate weight and rapid growth. For atmos- 
pheric carbonic acid were substituted oxalic and tartaric acids, their 
calcium compounds being found more favorable to the purpose. A for- 
mation of new leaves and an increase of weight of dry substance showed 
that these organic acids may, to a certain extent at least, take the place 
of carbonic acid in plant-nutrition. He further observed a decided 
exhalation of oxygen from water-plants, in direct sunlight, which had 
received very dilute solutions of oxalic or tartaric acid salts instead of 
carbonic acid. 
He next endeavored to determine in what manner this change of the 
two acids into cellulose and carbo-hydrates takes place. He considers 
it possible by two ways: by gradual liberation of oxygen, a reduction 
taking place, as Liebig believed; or they may be first oxidized to car- 
bonic acid, and from this condition further changed in presence of sun- 
light in the green leaves. To determine which of these metamorphoses 
takes place, the plants are inclosed in an atmosphere completely freed 
from earbonic acid. If, under such conditions, a reduction takes place, 
the plant can vegetate; but this is impossible if the acids must first 
change to carbonic acid by oxidation. Experiments in which the con- 
ditions thus described were observed showed that oxalic acid cannot be 
assimilated, that the plants rapidly diminish in weight and die. This 
proves Liebig’s theory to be incorrect, and that oxalic acid cannot be 
the transformation-link between atmospheric carbonic acid and the 
carbo-hydrates, and, consequently, it can enter into the process of nutri- 
tion only after previous oxidation to carbonic acid. This being estab- 
lished for oxalic acid, it will also hold good for the carboxyl group, 
oxalic acid Being a CO. OH compound. 
With tartaric acid and an atmosphere free from carbonic acid, very 
different results are obtained. The plants vegetate, though much more 
slowly than with admission of carbonic acid, the increase being only 
about one-half as great. This shows that, with tartaric acid, the alcohol 
groups may be changed directly into the formative material of the plant. 
This being accepted, the same law will hold good for the alcohol groups 
which have no analogous acids. This was clearly proven by growing 
plants with exclusion of atmospheric carbonic acid, and with glycerine © 
as the source of carbonaceous matter. 
It therefore appears that in presence of light the carboxyl group may, 
after previous oxidation, indirectly, while the alcohol groups may directly, 
enter into the formation of material in green plants. 
Experiments made with plants under similar conditions to deter- 
