Botany and Zoology. 159 
2. Maximowicz, de Coriaria, Ilice et Monochasma, ete. 
quarto paper in the Mém. Acad. St. Petersb., 1881. pp. 70, and four 
another. Monochasma is a new Chinese genus near to Bungea, 
and to Schwalbea is assigned a character for better distinguishing 
A. G. 
3. Ueber sogenannte Compasspflanzen. By Professor E. Sranu. 
—In this paper, which is an extract from the Jen. Zeitschrift, 
Stahl gives the result of his experiments with Lactuca Scariola 
and Silphium laciniatum, for the purpose of ascertaining the con- 
ditions which cause the leaves of the plants named to assume a 
meridional position. In the case of the Silphium, which is the 
common Compass-plant of the Western States, the fact that the 
: rder. Thos 
the north side of the stem become vertical by a twisting of the 
petiole, the upper surface of the leaf facing the east. Those on 
the south side by a similar twisting become vertical with the 
upper surface facing the west. The leaves on the east and west 
side of the stem do not exhibit any torsion of the petioles, but 
they become upright with their upper surfaces approximated to 
the stem. Stahl took two plants growing in pots and placed one 
where it would be exposed to direct sunlight from 10 o’clock 
onal position, but in the second case they did. That the meridi- 
iti he su i 
0 osition is produced by t n when near the horizon is 
clearly shown by the following experiment. A ith several 
young plants was placed in a window facing the north, where the 
plants received direct sunlight a few hours after sunrise b 
fore sunset. In this experiment the leaves bent ard the north 
with their upper surfaces turning either to the east or to the 
west. e pot was then placed farther back in the room, so that 
