ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
621 
and that “ The equivalents of regressive or progressive localised stages 
are to be sought in the adults of regressional or progressional series of 
groups.” A large number of illustrations are given, chiefly taken from 
the vegetable kingdom. 
Influence of Static Electricity on the Direction of Roots.* — Ex- 
perimenting on the roots of Vida Fciba , M. A. Letellier finds that 
positive static electricity exercises an influence on the direction of the 
primary and secondary roots opposite to that of the electric plate ; but 
the action of negative static electricity is much less decided, scarcely 
perceptible on the primary roots ; while the action on the secondary 
roots can be traced by a curve behind that which removes the roots from 
the negative plate. 
Dissemination of the Seeds of Razoumofskia.t — Prof. D. T. Mac- 
Dougal describes the structure of Bazoumofshia ( Arceuthobium ) robusta , 
belonging to the Loranthacese, parasitic on Pinus ponderosa, and charac- 
terised by the almost entire absence of chlorophyll, and by the leaves 
being reduced to minute bracts. The berry-like fruit has a peculiar ex- 
pulsion apparatus by which the seeds are thrown out to a considerable 
distance without external agency. The seed has the form of a rifle 
bullet, conical at the basal end and truncate at the apical end, with a 
general cylindrical outline. Its expulsion is effected by the rapid 
swelling of a layer of globoid cells with thick mucilaginous contents 
immediately surrounding the seed ; this causes the rupture of a scission- 
layer at the base of the fruit, which causes the seed to be thrown out to 
a distance of 2 or 3 metres. The seeds can germinate only on the young 
shoots of the pine, to which they become attached by the mucilage which 
they carry with them. 
Germination of Crinum Macowani.:J— Dr. J. H. Wilson describes 
the mode of germination of the seeds of this plant, which presents 
several peculiarities. The transference was demonstrated of stored food- 
material from the fleshy endosperm of the seed to the equally fleshy 
tissues of the bulb. 
Effect of various Substances on the Respiration and Assimilation 
of Submerged Plants.§ — From experiments on the influence on the 
growth of Elodea canadensis and MyriopJiyllum verticillatum of a variety 
of organic and inorganic substances, Herr B. Jacobi adduces the general 
law that the assimilation of aquatic plants is lowered in intensity, while 
the respiration is increased to an extent varying with the substance em- 
ployed. 
(3) Irritability. 
Geotropism of Roots.|| — Herr M. Wachtel has repeated Czapek’s 
experiments on the geotropism of roots, and has arrived at a very dif- 
ferent result, which altogether negatives the theory of a “ brain function ” 
of roots. He finds geotropic sensitiveness to be by no means a special 
* Bull. Soc. Bot. France, xlvi. (1899) pp. 11-23. 
t Minnesota Bot. Studies, 1899, pp. 169-73 (2 pis. and 1 fig.). 
X Trans. Bot. Soc. Edinburgh, xxi. (1899) pp. 211-6 (1 pi.). 
§ Flora, lxxxvi. (1899) pp. 289-327. 
|| Schrift. Naturf.-Gesell. Odessa, xxiii. (1899) (Russian). See Bot. Ztg., lvii 
(1899) p. 227. 1 Cf. this Journal, 1895, p. 454. 
1899 2 t 
