JMiscellanies. 375 
31. On the Sleep of Plants —M. Virey, in a memoir entitled, 
Flore Nocturne, (Flora nocturna) announces the following results or 
Jaws which he has deduced from his researches on this subject. Cold 
and humidity diminish the transpiration of vegetables; the sap, then 
insteadyof ascending to the summits of the leaves and flowers, as du- 
ring the day, descends towards the roots. Hence, the sap vessels of 
those parts, frail and fine-as they are in many plants, become almost 
empty and contract by their own elastic force. This is the reason 
why so many compound flowers, the Malvacez, the Convolvuli, &c. 
close during the night or even when the sky is covered with clouds. 
For a similar reason a numerous class of plants with pinnated leaves, 
fold them and sleep during the night. Thereturning warmthof the sun, 
again sets the sap in motion, and again invigorates the leaves and pet- 
als. ‘The heat and light dilate the vessels with a sort of turgescence, 
and expand the foliage until the return of night again drives the sap 
from their delicate vessels. But why is it otherwise with nocturnal 
plants which appear to languish and to be overcome during the day, 
and unfold their beauties only when the sun is withdrawn. It is be- 
cause his ardor acts too powerfully upon the frail texture of certain 
petals—evaporates too rapidly their nutricious juices, and causes 
them to close. But during the freshness of the night, these juices re- 
main in the tissue of the plant, fill their tubes and unfold their sur- ° 
faces to the atmosphere.—fev. Encyc. Aout, 1831. 
32. Shower of Flies. Singular appearance of the Moon.—At the 
session of the Academy of St. Petersburgh, held 21st of February, 
1831, a singular phenomenon was described which occurred at Orem- 
burg, on the 14th of December, 1830. During the whole of that 
day it rained heavily, although the thermometer remained at the 
freezing point. About midnight loud thunder was heard in the north- 
west ; and on the 14th of December snow fell, accompanied by a 
multitude of small black gnats, whose motions were similar to those 
of the flea. ‘The next day the atmosphere was clear, and the tem- 
perature fell to ten degrees below. At the same session a letter was 
read from the Governor of Oremburg, stating the following facts. 
On the 19th of January, 1831, between 6 and 8 P. M, the evening 
being fine, the new moon Leeited surrounded with a circle of fire, 
perfectly regular, and cut by two diameters of fire equally regular. 
The moon occupied the center of the circle. Two white semicir- 
cles were very distinctly delineated at the extremities of the diam- 
eter which went from E. to W. and their light was extended almost 
