ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
143 
ing or destitute of nitrogenous substances, the late Prof. B. Miiller- 
Thurgau concludes that nitrogen has both a direct and an indirect 
influence on the growth of plants; the former by the supply of material 
for the formation of proteid substances ; the latter by increasing the 
strength of the root-system, and thus enabling the plant to draw a 
larger amount of nutriment from the soil. 
Antidromy.* * * § — Mr. G. Macloskie gives further illustrations of this 
mode of growth, both dextrorse and sinistrorse. A forking rootstock (in 
Nuphar ) may produce antidromic plants on the two branches of the fork. 
The same phenomenon is illustrated in the stem of the fossil Lepido- 
dendron Sternbergii , and in the cones of Encephalartos Altensteinii. 
Ascent of Water in Trees. — Prof. F. Darwin gives a resume of all 
the more important observations and theories on this subject, including 
those of Sachs, Boehm, Strasburger, Schwendener, Dixon and Joly, and 
Askenasy,f pointing out the great importance of the discovery of Dixon 
and Joly that a confined column of water possesses a power of resisting 
tensile stress. According to the most modern views, imbibition, this re- 
sisting power of suspended threads of water, and the turgescence of the 
cells of the mesophyll, all play their part in the phenomenon. 
Prof. S. H. Y ines J calls special attention to the fact that a very 
considerable suction-force is developed by a branch independently of 
leaves or of life ; this force continues even after the branch has been 
actually killed. 
Prof. Joly § sums up his and Mr. Dixon’s conclusions as follows : — 
We have in the tracheal system of the plant a water-way which is freely 
open to water-movement, while closed to the movement of free gas. 
Every bordered pit is an open door to the sap, and a closed one to the 
gas-bubble, and one wdiicli locks and bars itself against the exit of an 
imprisoned bubble. In a word, it is a structure semi-permeable towards 
matter in the three states — the solid, the liquid, and the gaseous. 
Transpiration. || — Herr E. Krober contests the statement of Miiller- 
Thurgau that the energy of transpiration of a plant may be taken as the 
measure of its capacity for absorbing water. The amount of transpira- 
tion for different branches of the same tree differs as widely as that for 
different individuals of the same species, or even as much as that for 
different species. The energy of transpiration depends largely on the 
external conditions, both at the time of observation and at preceding 
periods. 
(3) Irritability. 
Transmission of Irritation in Sensitive Plants.! — Prof. D. T. Mac- 
Dougal describes an arrangement by which the effect of increased or 
decreased pressure on the sensitiveness of sensitive plants can be ob- 
* Bull. Torrey Bot. Club, xxiii. (1896) pp. 420-3, 536-7. Cf. this Journal, 1896, 
p. 541. 
f Ann. Bot., x. (1896) pp. 630-43. Cf. this Journal, 1895, p. 550. 
i Tom. cit., pp. 644-7. Cf. this Journal, 1896, p. 650. 
§ Tom. cit., pp. 647-60. Cf. this Journal, 1896, p. 542. 
t| Landwirthsch. Jahrb., xxiv. (1895) pp. 503-37. See Bot. Centralbl., 1896, 
Beih., p. 330. 
! Bot. Gazette, xxii. (1896) pp. 293-300 (1 pi.). Cf. this Journal, 1896, p. 89. 
