ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
373 
during the early period of the germination of the seed, and immediately 
after the opening of the flower. 
Radiation and Absorption of Heat by Leaves.* — Herr A. G. Mayer 
states that, with one exception (Arctium Lappa), in all the plants ex- 
amined by him the dark lieat-rays are radiated with equal intensity from 
the two sides of the leaf. In Arctium Lappa the radiation from the 
under side was only 81 per cent, of that from the upper side. A slight 
deposit of dew reduced the radiation to 78 per cent., a heavy deposit to 
66 per cent, of the normal intensity. The absorption of heat by leaves 
varied between 67 and 86 per cent., according to the species. 
Presence of Mannite in Wine (Mannitic Ferment).? — The presence 
of mannite in wine, especially the red wines of Algeria, Spain, and Italy, 
has only excited the attention of chemists during the past few years. 
MM. U. Gayon and E. Dubourg have isolated and cultivated on various 
natural and artificial media the mannitic ferment which was obtained in 
the first place from a white Algerian wine. The organism is a very 
small motionless rodlet, which collects in little heaps. In grape must 
or sweet wine it grows well, but still better in solutions of invert sugar 
to which 20-30 grm. of Liebig’s extract per litre have been added. 
Whatever the medium there is no cloudiness, no gas formation, and the 
ferment sinks to the bottom, where it forms a thin whitish deposit. It 
lives in the presence or absence of air equally well. The mere presence 
of mannite in any wine is easily detected by slowly evaporating without 
heat 2 or 3 ccm. of wine in a watch-glass ; if any mannite be present, 
there will be found after the lapse of 24 hours delicate acicular crystals 
which have a silky look and a radiating arrangement. The mannitic 
fermentation is favoured by the elevated temperature, and thus an 
indication for its prevention is afforded. By keeping the temperature of 
the fermentation vats below 30°, the production of mannite is quite pre- 
vented, and the alcoholic fermentation not interfered with. 
The authors further show that the mannite disease of wine is not the 
same as that when wine becomes tart or sour ; for the former does not 
develope in wines that are devoid of sugar, while the souring ferment is 
easily cultivated in such fluids. The volatile acid product of the 
mannitic fermentation is exclusively acetic acid, while in soured wine it 
is a mixture of propionic and acetic acids. From sour wine the cream 
of tartar disappears, but it is not decomposed by the mannitic ferment. 
The mannitic ferment differs in shape, size, and general arrangement 
from the ferment of sour wine. 
B. CBYPTOGAMIA. 
Cryptogamia Vascularia. 
Embryo of Ferns.? — Prof. G. F. Atkinson has observed that in 
Pteris serrulata and Adiantum cuneatum the two cells which result from 
the primary division of the oosphere are of unequal size (corresponding 
also to Goebel’s figure of the process in Adiantum capillus Veneris). The 
* Amer. Journ. of Sci., xlv. (1893) pp. 340-6. See Bot. Centralbl., lvi. (1893) 
p. 36. f Ann. Inst. Pasteur, viii. (1894) pp. 108-16 (1 fig.). 
X Bull. Torrey Bot. Club, xx. (1893) pp. 405-8. 
