ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
357 
Fixation of Free Nitrogen by Plants. — From experiments made 
on the oat, potato, colza, and grasses, MM. T. Schlcesing and E. Laurent* * * § 
conclude that, under the conditions employed, these plants have no 
appreciable power of fixing free nitrogen. 
On the other hand, as the result of experiments made on growing 
cress in river-sand watered by non-nitrogenous salts, Herr E. Breal f 
claims to have demonstrated the fixation of atmospheric nitrogen by the 
seedlings. The seeds of plants grown in this way were, however, 
lighter, and contained less nitrogenous matter, than those grown in 
ordinary soil. 
Herr A. Petermann J again confirms his earlier results that not only 
haricots, but also barley shows a gain of nitrogen, which must have been 
acquired directly from the air. 
Absorption of Atmospheric Nitrogen by Microbes.!— M. Berthelot 
has experimented on the power of low organisms to absorb nitrogen 
from the atmosphere. Both natural and artificial humic acid were 
placed in a flask with water containing a small quantity of the lower 
forms of vegetation which had developed in the presence of light. The 
flasks were then carefully stoppered, and exposed to diffused light for 
several months. While microscopic growths of many species developed 
under these circumstances, a certain amount of carbon dioxide was 
formed, and there was an appreciable increase in the amount of com- 
bined nitrogen. 
Influence of Anaesthetics on Transpiration. || — The following are 
the general results of a series of experiments made by Mr. A. Schneider 
on the influence of ether on transpiration in a number of plants. Ether 
retards protoplasmic action, and, in sufficient doses, kills the protoplasm. 
It retards assimilation, and, in this way, retards transpiration under all 
conditions. The increased loss of water in an anassthetized vegetable 
tissue is not due to transpiration, but to evaporation resulting from 
the death of the tissue. The periods of maximum growth and of maxi- 
mum transpiration coincide. 
(3) Irritability. 
Irritability of the Leaves of Dionsea.H — Dr. J. M. Macfarlane con- 
firms his previous statement that the bristles on the leaves of Dionsea 
muscipula require two successive stimuli to cause closure of the leaf. 
These stimuli may be exerted on the same bristle, or on different 
bristles on the same half, or on bristles on opposite halves of the leaf. 
The interval between the two stimuli may be as much as from 50 to 70 
seconds. The closing movement itself is limited to two seconds. With 
regard to the effects of water on the irritability, while raindrops or a 
slight current of water falling on the upper surface of the leaf are 
* Comptes Rendus, cxv. (1892) pp. 659-61. Cf. this Journal, ante, p. 68. 
t Ann. Agron., xviii. pp. 369-79. See Journ. Chem. Soc., 1892, Abstr., p. 1508. 
X Mem. Acad. Roy. Belg., xlvii. (1892). See Journ. Chem. Soc., 1893, Abstr., 
p. 33. 
§ Comptes Rendus, cxv. (1892) pp. 569-74. Cf. this Journal, 1892, p. 823. 
|| Bot. Gazette, xviii. (1893) pp. 56-69 (1 pi.). 
^ Contrib. from the Bot. Laboratory of the Univ. of Pennsylvania, i. (1892) 
pp. 7-44 (1 pi.). Cf. this Journal, 1891, p. 771. 
