1908) CURRENT LITERATURE 237 
an appropriate intensity of light in each case to balance the gravity stimulus 
without any effect on geotropic sensitiveness itself. Thus in the coleoptile of 
Avena sativa light of about 55 meter-candles, in the hypocotyls of Brassica Napus, 
Lepidium sativum, and Agrostemma Githago respectively 525, 666, 1026 m.-c., 
compensates gravity when each stimulus acts at go°. en equivalent light acts 
at right angles to gravity (plants vertical, light horizontal) the parallelotropic 
organs take a resultant position, departing about 45° from the direction of each. 
On the elimination of the one-sided action of gravity by the clinostat, however, 
they become parallel to the light rays; but even in the final position of rest they 
have not lost their sensitiveness to gravity. 
The geotropic series of reactions is quicker than the heliotropic, when the 
light is reduced to the compensating point; consequently, when light and gravity 
act antagonistically, the geotropic curvature a rs first, and the maximum of 
heliotropic stimulation does not appear until much later. While these results 
are strictly true only for the plants observed, yet the principle is probably valid 
for others.—C. R. B. 
Development of Juniperus.—Two preliminary accounts of fertilization in 
uniperus were noted in this journal (40:318. 1907). The two accounts differed 
mainly in regard to time relations, NoREN stating that the interval between 
pollination and fertilization was over a year, while SLtupsky claimed that the 
development from megaspore to embryo occupies only a single summer. The 
Present account‘? shows that Norn was right, SLupsKy having made a mistake 
in estimating the age of the cones. The pollen grain in the uninucleate condition 
reaches the nucellus the middle of June and soon divides into a tube cell and 
Senerative cell, the latter remaining undivided until the following May, when it 
forms the stalk and body cells. Early in July the body cell gives rise to two equal 
male cells. In the nucellus there are several sporogenous cells, only one of which 
divides to form megaspores, the others becoming a nutritive jacket about the 
functioning megaspore. Usually only three cells of the tetrad are formed. In 
the archegonium there are four neck cells; and a ventral canal nucleus is formed, 
but never becomes separated from the egg by a wall. Fertilization occurs about 
the middle of July and the fusion nucleus passes to the bottom of the egg, where 
€€ mitoses give rise to eight free nuclei which become arranged in two zones. 
Walls now appear and the cells of the upper zone divide to form the rosette and 
Suspensor 
The account is very full, cytological details of reduction and fertilization being 
figured and described —Cuartes J. CHAMBERLAIN. 
Hygroscopic movements of living leaves.—The leaves of some species of 
Rhododendron exhibit variation movements which follow the recurrence of 
vezing and thawing weather. The usual position of the leaves is horizontal, 
With the blade expanded. At freezing temperatures the edges of the leaves curl 
- : Nog, C. O., Zur Entwickelungsgeschichte des Juniperus communis. Upp- 
niversitets Arsskrift 1907: 1-64. pls. 4. 
