ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
219 
Assimilation of Ammoniacal Nitrogen and Nitric Nitrogen.* * * § — 
MM. B. Laurent, E. Marchal, and E. Carpiaux report the results of a 
series of observations on the assimilation of ammoniacal nitrogen and 
nitric nitrogen by the higher plants. The general conclusions are that, 
in the higher plants, the assimilation of nitrates does not take place in 
the dark ; the action of the ultra-violet rays is necessary for it. For the 
assimilation of ammoniacal salts, the action of the same rays is predomi- 
nant, but the luminous rays may incite a feeble assimilation of ammonia 
in etiolated leaves. The action of chlorophyll is not necessary ; etiolated 
leaves assimilate ammoniacal nitrogen even better than green leaves. 
The assimilation of nitric nitrogen gives rise to a temporary production 
•of ammonia. 
Function of Calcium Oxalate.j — From a series of observations, 
made chiefly on the rhizome of Humex obtusifolius, grown in various 
soils and in the dark, Herr G. Kraus has arrived at the conclusion that 
calcium oxalate is by no means invariably an excretory product, but 
that it performs the function of supplying the necessary lime for the 
aerial portions of the plant. Similar results were obtained as to the 
function of this substance in the bark of various trees and shrubs. With 
the Cactacese the results were mainly negative, though not conclusive. 
The only possible solvent for calcium oxalate in the cell-sap is a free 
-acid. 
Germination of Barley.J — Mr. T. 0. Day publishes a series of ob- 
servations on the germination of barley with restricted moisture, the 
results being shown in a number of tables. An increase of moisture 
during germination always induces a corresponding increase in the 
carbon dioxide produced. Taking the production of carbon dioxide as 
the measure of growth during germination, the period of greatest activity, 
with varying quantities of moisture, is generally about the third or 
fourth day. 
Influence of the Stock on the Graft.§ — By grafting the same variety 
■of the pear on two different stocks, the wild pear and the quince, 
MM. G. Riviere and G. Bailbache have attempted to determine the 
question of the influence exercised by the stock on the graft. They find, 
as a general result, that the mean weight of the fruit produced is con- 
siderably greater in the plants grafted on the quince ; that the density 
•of the fruit is also greater, and that the amount of free acid and of sugar 
is also larger. 
Vitality of Seeds.|| — As the result of further observations on this 
subject, Dr. A. J. Ewart states that the resistant power of a seed to 
desiccation is partly dependent on the nature and thickness of the seed- 
coats, partly on the form in which the reserve food-material is stored. 
Other conditions being similar, albuminous seeds are the least resistant 
to desiccation, oily seeds next, and starchy seeds most resistant. 
* Bull. Acad. Roy. Sci. Belgique, xxxii. (1896) pp. 815-65. 
t Flora, lxxxiii. (1897) pp. 51-73 (2 figs.). 
x Traus. Bot. Soc. Edinburgh, xx. (1896) pp. 492-501 (2 figs.). 
§ Comptes Rendus, cxxiv. (1897) pp. 477-80. 
| Proc. Liverpool Biol. Soc., x. (1896) pp. 185-90. Cf. this Journal, 1895, p. 72. 
