ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
69 
a histological examination. He finds that coalescence always depends on 
a new formation of cells, which combine organically in the same way as 
they do in an ordinary tissue. The cell-walls of the coalescing cells are 
living ; their protoplasm finely granular ; they contain active oxygen. 
Influence of Light and Moisture on Growth.* — Without asserting 
that turgor has no influence on growth, Prof. E. Godlewski maintains 
that it is by no means the most important factor. It is in the youngest 
parts of a plant, where turgor does not vary with the presence or 
absence of light, that growth shows the greatest variation between day 
and night. The author agrees with Askenasy in attributing a special 
influence on growth to protoplasm, which is easily understood if we 
suppose the cell-wall to be permeated with living protoplasm. The 
solar rays exercise a retarding influence on growth, but not an imme- 
diate one ; since, in the case of Phaseolus multijlorus, the stems lengthen 
more by day than by night. Any diminution of moisture in the air 
causes a sudden but transitory retardation, an increase of moisture a 
transitory increase in the rapidity of growth. A great increase in 
temperature also causes retardation of growth. The temperature of tho 
soil has scarcely any influence on growth. In etiolated plants tho 
phenomena are very irregular in this respect. 
Influence of Atmospheric Electricity on the Growth of Plants.f — 
From experiments made chiefly on Lactuca Scariola, Zea Mays, Triticum 
sestivum, Nicotiana Tabacum, and Vicia Faba, Prof. A. Aloi has arrived 
at tho conclusions that atmospheric electricity exercises a beneficial 
influence on the growth of plants ; that tho electricity of the soil has 
a similar influence on tho germination of seeds; and that the less 
luxuriant vegetation of plants which grow in the neighbourhood of trees 
is duo in great part to the diminution of temperature. 
Influence of Depth in the Soil on Germination-! — Herr Kraus 
shows that the vigour of vegetation during germination may depend on 
tho depth at which the seed is planted in the soil ; when this is too near 
the surface tho seedling is not vigorous. The optimum depth for each 
6pecies does not depend in any way on the size of the seed. Leguminous 
seeds are, within certain limits, indifferent to the depth at which they 
are planted. Vegetative reproductive organs, such as the eyes of 
potatoes, are subject to the same law. 
Action of Poisons on the Germination of the Seeds of the Plants 
which produce them.§ — M. C. Cornevin has investigated this subject, 
especially in reference to saponine, cytisine, nicotine, and narcotine. In 
the cases where the poison is formed in tho seed, as saponine in those 
of Agrostemma Githago, and cytisine in those of Cytisus Laburnum, its 
presence offers no hindrance to the germination of the seed. Where the 
poison occurs in some other part of the plant than the seed, as in the 
latex, the effect of bringing seeds of the same plant into contact with it 
varies. Seeds of the tobacco plant brought into contact with nicotine 
* Anz. Akad. Wiss. Krakau, 1889 and 1890. See Bonnier’s Rov. Ge'n. de Bot., 
iii. (1891) p. 327. Cf. this Journal, 1890, p. 630. 
t Malpighia, v. (1891) pp. 116-25. 
% Forsck. aus d. Geb. d. Agrioulturphysik, 1890. See Bonnier’s Rev. Gen. de 
Bot., iii. (1891) p. 438. § Comptes Rendus, cxiii. (1891) pp. 274-6. 
