ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
195 
Influence of a Dry Soil on the Size of Leaves.* — From a series of 
experiments made on a variety of herbaceous plants, M. E. Gain comes 
to the conclusion that the statement made by nearly all writers that 
dryness of the soil acts prejudicially on the development of the surface 
of leaves is far too general. On some plants it has precisely the opposite 
effect ; other conditions, such as the natural habit and the need of the 
species for shade or for insolation, must also be taken into account. 
Frost-forms of Leaves.f — Prof. C. Luerssen describes the modifica- 
tions observed in Prussia in the winter-forms, chiefly of the leaves of 
Nephrodium Filix-mas and Athyrium Filix-femina , and in Equisetum 
sylvaticum. They consist mainly in a reduction in length of the pinnae 
of the leaves of the ferns, in a partial suppression of the parenchyme of 
the upper portion of the leaf or of the pinna, and in a persistent circina- 
tion of the apices of the pinnae. The leaves are usually fertile, but the 
sori are often small. 
Variation in Cotyledons.^ — Herr H. deVries points out how greatly 
the number of cotyledons is liable to vary among Exogens, even in the 
same species, and proposes the following terms: — Tricotyledons , with 
three cotyledons ; Hemitricotyledons, with one normal and one divided ; 
Tetracotyledons , with four ; Hemitetracotyledons , with two divided, or two 
normal and one divided ; Syncotyledons, with the two cotyledons coalescent 
into a single leaf ; Amphicotyledons when the two united cotyledons form 
a cup. These can all, to a certain extent, be perpetuated by heredity. 
The first is by far the most common. 
Fasciation.§ — From the examination of a large number of instances, 
Dr. A. Nestler has come to the conclusion that fasciation is not the result 
of the coalescence of two or more axes, but of the broadening of a single 
normally cylindrical axis, caused by a peculiar change in the grow- 
ing apex. True fasciation must therefore be distinguished from abnor- 
mal growths, the result of cohesion or adhesion. An excessive supply 
of food-material cannot be regarded as the primary cause of fasciation. 
Aerial Bulbils of Lilium tigrinum.|| — According to M. L. Dufour, 
the bulbs on the stem of this lily can be greatly increased in size by 
removing the flowers and the upper portion of the stem. They do not 
lose their power of germination by drying to a large extent. Up to a 
certain point the strength of the plant is not proportioned to the size of 
the bulb from which it springs. 
1 8. Physiology. 
Cl) Reproduction and Embryology. 
Gynodioecism.lf — Mr. J. C. Willis records the results of further ob- 
servations on this phenomenon, especially among the Labiatse. He finds 
* C.R. Ass. Franc, pour l’Avance. d. Sci., 1893 (1894) pp. 585-91. See Bot. 
Centralbl., 1894. Beih., p. 418. 
t Biblioth. Bot. (Luerssen and Frank) Heft’28, 1894 (58 pp. and 23 pis.). 
•j Ber. Deutsch. Bot. Gesell., xii. (1894) pp. 25-39 (1 pi.). 
§ Oesterr. Bot. Zeitschr., xliv. (1894) pp. 343-6, 369-74, 410-5, 456-9 (2 pis. and 
figs.) ; SB. K. Akad. Wiss. Wien, ciii. (1894) pp. 153-68 (2 pis.). 
l| C.R. Ass. Franp. pour l’Avauce. d. Sci., 1894, pt. ii. pp. 527-33. See Bot. Cen- 
tralbl., lx. (1894) p. 117. 
Proc. Cambridge Phil. Soc., viii. (1894) pp. 129-33. Cf. this Journal, 1893, p. 503. 
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