ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
145 
tion of proteid takes place. In the formation of proteids from grape- 
sugar, ammonium chloride or sulphate may take the place of asparagin. 
Contrary to the statement of some other observers, Hansteen asserts that 
light has no, or very little, direct influence on the formation of proteids. 
Formation and Dissolution of Hemicellulose.* — Dr. J. Griiss has 
studied the formation and dissolution of cell- walls composed of cellulose, 
and its connection with the formation of gum. He states that the hemi- 
celluloses mannan, galactan, and araban are formed directly or indirectly 
as reserve-substances. In the first case, this takes place as thickened 
walls in the endosperm ( Phoenix , Phy telefilms), or as secondary thick- 
ening-layers in libriform and wood-parenchyme cells ( Primus , Acacia , 
Astragalus). They take the form of indirect reserve-substances when 
they compose the walls of starch-bearing cells, as in the endosperm of 
grasses. In a cell-wall composed of a mixture of two hemicelluloses, 
one of the two constituents is decomposed sooner than the other by the 
action of diastatic enzymes. The hemicelluloses galactan and araban 
are transformed by enzymes into the gums arabin and galactin, and 
may pass as such into the tissue before they become converted into the 
sugars arabinose and galactose. These gums occur in the dormant re- 
serve-reservoirs in PrunuSj Acacia, and Astragalus , and may be termed 
“ reserve-gums.” 
Respiration of Wounded Plants.f — Mr. H. M. Richards gives the 
results of a series of experiments on the effect of injury to the tissue on 
respiration in the case of a number of plants, the potato, bean, carrot, 
and others. The general immediate result of injury is a greatly increased 
respiration, falling to the normal intensity as the wound heals. This 
increase may be ascribed to an effort on the part of the plant to recover 
from the injury, by which the ordinary functions are stimulated, thereby 
necessitating an increased supply of oxygen. In bulky tissues there is, 
in the natural condition, a certain amount of enclosed or absorbed carbon 
dioxide, some of which is given off very suddenly during the first two or 
three hours after injury. The ratio of the absorption of oxygen and 
production of carbon dioxide does not appear to vary within very wide 
limits before and after injury. The amount of oxygen absorbed is always 
in excess of the amount theoretically required for the quantity of carbon 
dioxide evolved. 
Nitrification. — In confirmation of previous results Herr E. Godlewski J 
concludes, from a fresh series of experiments, that nitrifying organisms 
derive their carbon from free carbon dioxide and not from carbonates. 
The amount of free nitrogen produced varies with the conditions of the 
experiment. 
As the result of experiments M. Mareille § states that the energy with 
which a soil is nitrified depends not only on the temperature, aeration, 
and humidity of the soil, and on the energy of the organisms present, 
but also on the nature of the organic matter to be nitrified. 
* Biblioth. Bot. (Luerssen u. Frank), Heft 39, 1896, 15 pp. and 1 pi. 
t Ann. Bot., x. (1896) pp. 531-82 (2 figs.). 
% Anzeig. Akad. Wiss. Krakau, 1895, pp. 178-92. See Journ. Ohem. Soc., 1896, 
Abstr., p. 6(J8. 
§ Ann. Agron., xxii. (1896) pp. 337-14. See Journ. Chem. Soc., 1896, Abstr., 
p. 669. 
1897 
L 
