ZOOLOGY AND BOTANY, MICROSCOPY, ETC 
49 
large size of the transpiring surface in comparison with the transpiring 
mass; the position of the leaves and other characters which serve to 
diminish transpiration ; the thickness of the cuticle, deposition of wax, 
formation of mucilage, &c. ; the number, size, distribution, position, and 
structure of the stomates ; special peculiarities of individual species. 
Contrivances for reducing transpiration appear to be as necessary for 
bog as for xerophilous plants. It may often happen, therefore, as in 
Carex, that we find in the same genus, bog-species and xerophilous 
species with very little apparent difference in structure. With regard 
to the stomates, all the bog-species examined possess the power of 
closing them ; as a rule they are closed at night. 
Polymorphy of the Spruce Fir.* — Herr C. Schroter describes in 
detail the variations which occur in the spruce fir, Picea excelsa, in the 
habit, the size of the cones, the size and shape of the leaves, and other 
morphological characters. He derives from his observations the general 
conclusions that a variation in a given direction may be much more 
stable in one species of Pirns than in another, and that the same peculi- 
arity of habit or of some special point of structure may be induced in 
different species by quite different causes. 
Spiral Structure of the Hoots of Chenopodiacese.f — M. G. Fron 
attempts to explain in the following way the spiral structure of the roots 
of certain Chenopodiaceee belonging to the sub-orders Spirolobese ( Suseda , 
Salsola) and Cyclolobeoe (Beta, Spinacia , Atriplex, Chenopodium). The 
seed presents, on longitudinal section, an embryo surrounding a copious 
starchy endosperm. During its development the embryo, attached to the 
suspensor by the radicle, coils all round the endosperm, the cotyledons 
absorbing only a small quantity of the nutrient material which surrounds 
them. The apex of the cotyledons comes into contact with the radicle, 
but, as it continues to develope, covers it on the inner side along its 
whole length, and compresses it. This mechanical compression of the 
cotyledons on the radicle causes an asymmetry of structure, which is 
shown, on transverse section, by the arrangement of the tissues in a 
double spiral. 
Roots of Bignonia4 — Mr. T. G. Hill decides in the affirmative the 
disputed question whether the roots of Bignonia exhibit the same anoma- 
lous structure as the stem. The peculiarity consists in the arrest of the 
development of the secondary xylem, the depressions thus formed being 
filled up by wedge-shaped masses of phloem. Four of these phloem- 
wedges occhf in the root as well as the stem. The roots of B. unguis 
also possess the peculiarity of swelling out at intervals into tuberous 
growths. 
Physiology. 
(I) Reproduction and Embryology. 
Embryology of Aconitum.§— In the mode of impregnation and the 
development of the embryo in Aconitum Napellus, Herr A. Osterwalder 
* Vierteljahrssch. Naturf. Gesell. Zurich, xliii. (1898) pp. 125-252 (37 figs., 
1 table). t Comptes Rendus, cxxv. (1898) pp. 563-5. 
X Ann. of Bot., xii. (1898) pp. 323-8 (1 pi.). 
§ Flora, lxxxv. (1898) pp. 254-92 (6 pis.). 
1899 
E 
