ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 119 



Further obseryation lias convinced him that rotating nutation or circum- 

 nutation is not an independent or spontaneous movement, but that it arises 

 from the co-operation of at least two factors, negative geotropism and an 

 external or internal force, which factor displays itself in the unequal growth 

 of the two sides of every growing and rotating stem or tendril. In every 

 growing zone, even the youngest, of internodes capable of coiling, there is 

 a sensitiveness to the action of gravitation ; in other words, every such 

 zone is negatively geotropic ; and this combines in its effects with the 

 homodromous or transverse curvature resulting from the unequal growth 

 above referred to, which Wortmann proposes to call the " flank-curvature " 

 (Flanken-Kriimmung). According as the right or left side grows the 

 faster, the organ in question curves to the left or the right respectively. 

 This movement he regards, not as geotropic, but as purely spontaneous. 



Commenting on the same paper, Herr F. Noll * justifies his distinction of 

 different kinds of coiling into simple and comj)licated, " clasping movement " 

 and torsion taking no part in producing the former. 



Absorption of Water in the fluid state by Leaves. — Herr L. Kny | 

 refers to statements made by different writers as to the power possessed, 

 under certain circumstances, by the aerial organs of many plants, to absorb 

 water in the fluid condition, especially those of Lundstrom, whose results 

 he is unable to confirm. Among a number of plants examined, Dipsacus 

 laciniatus and FuUonum were the only ones which manifested this faculty. 

 In these plants the small quantity of water absorbed by the leaves could 

 only be of the very slightest advantage to the mature leaves, though it 

 might be to the upper portion of the stem and the leaves of the terminal 

 bud and inflorescence. 



To this Herr A. N. Lundstrom J replies that, while he is able to state 

 with confidence that some plants, e. g. Stellaria media, do under certain 

 conditions absorb water through the leaves, he has not maintained this to 

 be a universal phenomenon ; but that the most important direct beneficial 

 effects of rain and dew on the leaves of plants consist in washing the 

 leaves and in regulating the transpiration in the way of either increase or 

 dimiuution. 



(7) Chemical Processes (including' Fermentation). 



Moist Gangrene of the Cauliflower.§ — Prof. O. Comes has investigated 

 the cause of this disease, very prevalent in the neighbourhood of Naples, 

 which manifests itself in all the vessels being filled with gum. He finds in 

 the plants attacked the parasitic fungus Pleospora Napi or its conidiiferous 

 form Sporidesmium exitiosum, generally considered to be the cause of the 

 disease, as well as Cladisporium and Macrosporium Brassicee ; but regards 

 these fungi as merely accessory phenomena ; and believes the soiu'ce of the 

 disease to be gummy degeneration and putrid fermentation of the tissues, 

 caused by too great richness of the soil, and a too abundant supply of water. 



Exchange of Gases by Buds.|| — M. L. Mangin has experimented on 

 the changes produced in the surrounding atmosphere by recently detached 

 buds of various trees. The results vary with different species. As a 



* Bot. Ztg., xliv. (1886) pp. 738-40. 



t SB Versamml. Deutsch. Naturf. u. Aerzte, Sept. 22, 1886. See Bofc Ceutralbl., 

 xxviii. (1886) p. 125. 



X Bot. Oentralbl., torn, cit., p. 317. 



§ Atti R. 1st. Incorragiameiito Sci. Nat., iv, (1885). See Bull. Soc. Bot. Frauce, 

 viii. (1886) Rev. Bibl., p. 128. 



II Bull. Soc. Bot. France, viii. (1886) pp. 185-90. 



