356 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
co-operation of living cells. The ascent of sap to a height of 150 or 
200 feet from the root-hairs is not explicable as a purely physical 
phenomenon. 
Nutrition of Pines by Mycorhiza.* — Herr B. Frank records the 
results of a series of experiments on the growth of Firms excelsa with 
and without mycorhiza. Of 12 seedlings sown in pots and grown 
in the open air, 4 were left un sterilized, while the soil in the other 
8 was sterilized in the ordinary way. During the first year the 
growth of the 12 seedlings was nearly uniform; but in the second 
year those in the unsterilized pots all showed a decidedly more vigorous 
growth, which was much more strongly displayed in the third 
year ; and in all these 4 plants the root was thickly covered with a 
mycorhiza-felt. In the 8 sterilized pots, with one exception, the root- 
system was much more feebly developed, there was no mycorhiza, and 
the size of the seedlings was much less. One of the 8 showed a better 
growth, and there was a certain amount of mycorhiza on the roots. 
Herr Frank concludes from these facts that the seedlings depend largely 
for their nutrition on the mycorhiza-fungus, and that it belongs to one 
or more species the spores of which are not present in the air in great 
abundance. 
Adaptation of the Root to vital conditions. t— By experiments on 
cultivated plants — bean and oat — Herr C» Kraus demonstrated the 
power of the root to adapt itself to the conditions of the soil in which it 
grows, especially in the feebler development of the tap-root, and the 
stronger development of horizontal roots in a shallow layer of rich soil. 
The main purpose of the tap-root appears to be a mechanical rather than 
a nutritive one. 
Water Culture of Plants. :£ — Prof. J. Wortmann recommends large 
glass cylinders for the cultivation of plants in water, instead of the 
ordinary method. He finds, especially in cultures on this mode, that 
the root-system attains a remarkable development, resembling that of 
plants grown in the soil. 
Influence of Moisture on Vegetation.§ — From experiments on the 
cultivation of a number of plants, M. E. Gain draws the conclusion that 
the moisture of the soil and that of the air have very different effects on 
vegetation. The observations were made chiefly on the influence of 
different conditions of moisture on the flowering of the plants. The 
general result was that a moist soil is favourable, a dry air very favour- 
able ; while a dry soil is unfavourable, a moist air very unfavourable, to 
flowering. 
Effects of Freezing on Absorption and Evaporation. || —From ex- 
periments on a variety of plants (vine, bean, peach, pear, &c.), M. A. 
Prunet finds that, when branches have been frozen and again thawed, 
the evaporation from them is at first excessive, while at the same time the 
absorption of water is reduced much below the normal. The phenome- 
non of transpiration is converted into one of simple evaporation. 
* Ber. Deutscli. Bot. Gesell., x. (1893) pp. 577-83 (1 pi.). 
t Forsch. a. d. Geb. d. Agriculturphysik, xv. pp. 231-86. See Bot. Centralbl., lii. 
(1892) p. 312. X Bot. Ztg., 1. (1892) pp. 640-6 (3 figs.). 
§ Comptes Rendus, cxv. (1892) pp. 890-2. || Tom. cit., pp. 961-6. 
