272 SUMMARY OF CURRENT RESEARCHES RELATING TO 



substance is therefore not a reserve-material, as bad previously been, 

 supposed. These glucosides may be regarded as derivatives of the 

 molecules of albumen, and as stages of transition between the 

 albuminoids and carbohydrates, which circulate through the plant. 



Behaviour of Tannin in Germination.* — P. Eulf has examined 

 the part played by tauuin in the gerniiuation of the seeds of various 

 plants — Acer platanoides, A. pseudoplatanus, Fraxinus excelsior, Vicia 

 Faha, and Cijnoglossum officinale — and finds that it differs according 

 to the species ; and that, especially in the early stages, its true 

 function is still obscure. 



Laws of Growth of Vegetable Organs : Roots.f — E. v. Wettstein's 

 researches on this subject, of which we have already given a summary ,t 

 are now published in detail. 



Motions of Eoots during Growth.§ — The researches of J. Wiesner, 

 of which a summary has been given, || are also now published in detail. 



Autumnal Foliage.t — A. T. Fraser suggests from observations in 

 the extreme north of Scotland, where no forest trees can be got to 

 grow, that leaves fall in autumn from trees growing above a certain 

 latitude — about 30^ — through loss of vitality' in the more or less 

 highly polarized light. " Where the light is polarized, trees are 

 scarce or absent, mown by a swathing light ; and in the tropics, where 

 there is little polarization, they are luxuriant and green all the year 

 round." Leaves fall everywhere of course, but in the higher 

 latitudes the fall is en masse in the autumn ; while more south it is 

 in continuous driblets only. 



Respiration of Germinating Seeds.** — G. Bonnier and L. Mangin 

 divide seeds into two classes dependent on the difference of phenomena 

 with respect to respiration during germination : — 1. Oleaginous seeds 

 absorb during germination a volume of oxygen greater than that of 

 carbonic acid exhaled ; the excess of oxygen absorbed is employed in 

 tlie oxidation of the fatty reserve-substances during their transforma- 

 tion into starch. There is therefore assimilation of oxygen during 

 this period of the life of the seeds. 2. Amylaceous seeds are charac- 

 terized physiologically by the constant equality which exists between 

 the volume of oxygen absorbed and that of carbonic acid exhaled. In 

 these cases, therefore, there can be no assimilation of oxygen. 



Influence of Gravitation on the Movements of Stamens.ft — Dr. 

 J. Dufour points out that in a great number of flowers, the stamens, at 

 first straight, present at the end of some hours a strong curvature, 

 the concavity of which faces upwards. This curvature, which gene- 

 rally coincides with the opening of the anthers, is therefore very 



* Zeitschr. f. Naturwiss., Ivii. (1884) pp. 40-66. See Bot. Centralbl., xx. 

 (1884) p. 259. 



t SB. K.K. Akad. Wiss. Wien, Ixxxis. (1884) pp 59-113. 



X See this Journal, iv. (1884) p. 772. 



§ SB. K.K. Akad. Wiss. Wien, Ixxxix. (1884) pp. 223-302. 



11 See this Journal, iv. (1884) p. 589. 



^ Nature, xxxi. (1885) pp. 388 and 482. 



*» Bull. Soc. Bot. France, xxxi. (1884) pp. 3t)6-9. See this Journal, ante, 

 pp. 97, 104. 

 tt Arch. Sci. Phys. ct Nat., xii. (1884) pp. 417-8. 



