ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
411 
Embryology of the Rubiaceae.* — In the genera Ruhia, Houstonia , 
SJierardia , Vaillantia , Crucianelln , and Galium, , Mr. F. E. Lloyd finds 
that in the hypoderm of the nucellus 8 or 10 megaspores develop ; many 
of these germinate, becoming quadrinucleate ; one, or sometimes two, 
become perfect embryo-sacs with antipodals. One of the antipodals is 
very large, filling up the whole lower half of the embryo-sac in Sherardia , 
Rubia , and Galium. The suspensor is divided into two regions, micro- 
pylar and embryonal. The latter is composed of disc-shaped cells ; 
the former of large cells swollen out laterally, forming absorbing organs 
which become applied to the endosperm. 
Fertilisation of Viola.j — Mr. T. Meehan suggests that in some 
species of Viola— V. cucullata and tricolor — the pollen-tubes must reach 
the ovules in some other way than through the stigma and style. V. 
cucullata flowers at a period of the year when there are very few winged 
insects, and the membranous appendages to the anthers are so closely 
adpressed to the style as to render it almost impossible for the pollen- 
grains to reach the stigma. And yet the great majority of the flowers 
produce capsules with fertile seeds. The same is also the case with 
V. tricolor. Mr. Meehan regards the so-called stigmatic opening at the 
apex of the thickened style as a nectariferous gland. 
Biology of Pollen.J — Herr B. Lidforss adduces further evidence in 
favour of his contention that moisture is not generally destructive of the 
germinating power of pollen-grains, and criticises adversely the method 
pursued by Hansgirg.§ This power of resistance of pollen to moisture 
is often greatly influenced by external conditions ; it is greatly enhanced 
in moist air. The connection between the exposure of the pollen and 
its power of resisting moisture is traced out in a large number of cases. 
As a rule, those pollen-grains which are unable to resist moisture ger- 
minate very rapidly. 
The pollen-grains of ancmophilous plants are, as a rule, characterised 
by their comparatively small size. While containing a larger proportion 
of starch, they have less nitrogenous matter than those of entomophilous 
plants. 
Sex in Flowers. || — Mr. T. Meehan adduces the American Corylus 
rostrata as an additional example of the law previously enunciated by 
him, that, in the earliest stages of its life, the sex of a flowei-bud is 
not determined, and that its final development as a male or female 
flower is the result mainly of differences in the supply of nutrition. 
(2) Nutrition and Growth (including- Germination, and Movements 
of Fluids). 
Nutrition of Plants by Nitrogenous Substances.' f — A series of 
experiments by M. L. Lutz on the feeding of plants by various organic 
nitrogenous substances has led to the following results. It is possible 
* Bot. Gazette, xxvii. (1899) pp. 120-1. 
t Proc. Acad. Nat. Sci. Philadelphia, 1899, pp. 92-5. 
X Jahrb. f. wiss. Bot. (Pringsheim), xxxiii. (1899) pp. 232-912. Cf. this Journal, 
1896, p. 437. § Cf. this Journal. 1898, p. 319. 
II Proc. Acad. Nat. Sci. Philadelphia, 1899, pp. 84-6. 
Ann. Sci. Nat. (Bot.), vii. (189.0 pp. 1-103. 
