360 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Scattering of the Pollen in Ricinus.* * * § — Prof. F. Delpino describes 
the mechanism by means of which the anthers of Bicinus communis — a 
strictly anemophilous species — suddenly open to discharge their pollen, 
and which differs from the mechanism for a similar purpose in some 
Urticaceae. It consists of four distinct movements, viz. : — (1) a move- 
ment of separation resulting from the opening of the valves ; (2) a 
movement by which the lamina of the valve changes from concave to 
convex on its internal face ; (3) a movement by which the lamina 
changes suddenly from convex to concave ; (4) a movement by which 
the valves again approach one another. 
(2) Nutrition and Growth (includingr Movements of Fluids). 
Parasitism of the Mistletoe.-f — Dr. C. v. Tubeuf points out the 
want of definiteness in the particulars of the composition of the ash of 
the mistletoe hitherto recorded. In order to learn the laws which 
govern the drawing of the nutriment of the parasite from the host, we 
want to know the age of the leaves, whether one or two years, on what 
part of the host it is parasitic, and to have a comparison of the ash of 
the host and of the parasite. The author records examples of the 
parasitism of the mistletoe on itself, on Loranthus europse^is, and on 
different species of Quercus. 
Effect of the “Ringing” of Sterns.^— Prof. R. Hartig points out 
that by the “ ringing ” of the bark of trees below the lowest leafy 
branch, growth and the deposition of food-material are limited to the 
portion of the trunk above the ring. If the tree is young this results in 
its early death ; but if it has already attained a considerable age, it may 
survive the ringing for a long period. The explanation of this appears 
to be afforded by the fact that the ultimate ramifications of the roots of 
such trees effect a union of growth with those of other uninjured trees 
of the same kind growing in the immediate vicinity, and from these 
absorb the food-material which they require for the growth of their roots 
and the portion below the ring. 
Influence of Light on the vital conditions of plants.§ — From the 
results of a series of experiments made on partially or entirely darkened 
leaves, Herr J. Busch draws the conclusion that the decomposition of 
chlorophyll is not a primary consequence of darkness, but that chloro- 
phyll may^remain as such unchanged for any length of time in the plant, 
if the cell itself remain in a living state, and that the destruction of the 
chlorophyll in the dark is the result of the death of the cell. 
Influence of Thinning on the diametric growth in Fir-forests. || — 
M. E. Mer states that thinning favours the growth both in height and in 
diameter of the reserved trees. It is at the base of the trunk that the 
* Malpighia, iii. (1889) pp. 337-8. 
t SB. Bot. Verein Miiuchen, Dec. 9, 1889. See Bot. Centralbl., xli. (1890) 
pp. 43, 78, 80, and 135. Cf. this Journal, 1888, p. 86. 
t SB. Bot. Ver. Miinchen, Jan. 13, 1890. See Bot. Centralbl., xli. (1890) 
pp. 251 and 283. 
§ Ber. Deutsch. Bot. Gesell., vii. (1889), Gen.-Versamml.-Heft, pp. 25-30. 
II Bull. Soc. Bot. France, xxxvi. (1889) pp. 412-4. Cf. this Journal, 1889, 
p. 669. 
