72 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
which compose the primary and secondary motor nodes (those of the 
entire leaf and of the leaflets), caused by the greater amount of light and 
heat to which the upper one of the two is subject in the morning. If 
exposed either to continuous darkness or to continuous light, the move- 
ments will continue for some days, but with decreasing energy, and will 
finally cease altogether, 
(4) Chemical Changes (including Respiration and Fermentation). 
Formation of Albuminoids.* — In order to test the correctness of 
the theory that the chromatophores are the seat of the synthesis of the 
albuminoids in plants, M. Chrapowicki cultivated plants of Phaseolus 
vulgaris , Cucurbita Pepo, and Zea Mays in a non-nitrogenous saline 
solution obtained by replacing the potassium and calcium nitrates in 
Knop’s solution by potassium chloride and calcium sulphate. The 
development was at first normal, but was soon retarded and finally 
entirely arrested. The leaves were cut off and placed in normal Knop’s 
solution, and the formation of the albuminoids watched under the 
Microscope. They were formed at the expense of the nitrates in the 
solution, and always made their appearance first in the chromatophores. 
■y. General. 
Action of Solar Heat on the Floral Envelopes.! — M. E. Roze has 
endeavoured to determine by experiment whether the direct effect of the 
sun’s heat varies with the different colours of flowers. When a flower 
which has opened in the shade is suddenly exposed to solar radiation, 
it absorbs at first a certain quantity of heat, then rapidly gives off a large 
portion of this caloric, and, if then again placed in the shade, gradually 
loses the absorbed heat, and places itself in equilibrium with the 
temperature of the surrounding air. Red or violet floral envelopes 
absorb and give off more rays of heat than blue or yellow, and these 
latter more than white. A thermometer placed over the first rises, when 
transferred from the shade to the sun, as much as 8 3 ; one over the second 
6°-7 D ; over the third 5°-6° ; while over green leaves it does not rise 
more than from 2° to 3°. These latter absorb as much heat as petals, 
but give off again only a small quantity. This radiation of heat from 
the petals has probably a great effect in promoting the dehiscence of 
the anthers. The author found also that heat is powerfully absorbed by 
the soil from the sun’s rays, and is given off again to the whole plant, 
and especially to the parts in contact with the earth. A thermometer 
placed above the prostrate leaves of Plantago major rose to 44°, and 
in the case of Hypochseris radicata to 46', while the temperature of the 
surrounding air was only 28°. 
Biology of the Ericaceae.! — M. L. Fliche has examined various 
species of Ericaceae with a view to determine the quantity of mineral 
elements which they require. He finds that the plants belonging to 
* Arb. St. Petersburg Naturf. Gesell., xviii. See Bonnier’s Rev. Gen. de 
Bot.. ii. (1890) p. 359. 
t Bull. Soc. Bot. France, xxxvi. (1889), Aetes du Congres de Bot., pp. ccxii.-ccxiv. 
1 Rev. des Eaux et Forets, Nov. 10, 1889, See Bull. Soc. Bot. France, xxxvii. 
(1890), Rev. Bibl., p. 107. 
