ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
69 
Abnormal Germination of Acer platanoides.* * * § — M. L. J. Leger 
finds that in about 4 per cent, of the instances examined the.germination 
of the seeds of Acer platanoides was abnormal; the irregularity was in 
the following directions: — (1) one of the two cotyledons was more or 
less bifid ; (2) the number of cotyledons was three ; (3) each of the two 
cotyledons was split for 1/3 of its length ; (4) the number of cotyledons 
was four. The structure of the cotyledons is described in each of these 
cases, especially in regard to the arrangement of their vascular bundles. 
Dissemination of the Seeds of Harpagophyton.| — Herr P. Ascherson 
calls attention to the remarkable way in which the seeds of Harpago- 
phyton (Pedaliaceae) are disseminated in South Africa. The seed- 
vessels growing on the prostrate branches are covered with hooked 
appendages, which become fixed in the hoofs of antelopes and cattle. 
The violent stamping of the animal to get rid of the annoyance splits 
the hard pericarp and scatters the seeds. The characteristic hooked 
bristles on the seed-vessels are found even in the aquatic genus of the 
order, Trapella.\ Sesamum Schinzianum is characterized by the unusual 
occurrence on the same species of both extra-floral nectaries and a viscid 
hairy covering of the axis. 
(2) Nutrition and Growth (including- Movements of Fluids). 
Relations between Host and Parasite.§— Prof. H. Marshall Ward 
discusses some of the relations between host and parasite in certain 
epidemic diseases of plants. He shows that the conditions which are 
unfavourable to the vitality of the host are, in general, favourable to the 
rapid development and propagation of the fungus-parasite, causing 
especially thinness and softness in the cell-walls, and a greater perme- 
ability and less resistance in the protoplasm, with a larger proportion 
of organic acids, glucoses, and soluble nitrogenous constituents in the 
cell-sap. In the case of some of the fungi which are most destructive 
to plants, while the botrytis-form is saprophytic, the mycele is truly 
parasitic in the tissues of the host ; and this latter is especially vigorous 
and destructive where the botrytis-form has had abundaut food-material 
to live upon. In addition to a ferment or enzyme, the hyphm of the 
mycele have the power of developing large quantities of oxalic acid, 
which is especially destructive to the protoplasm of the host. Whether 
a given fungus exists as a parasite or as a saprophyte is, to a large extent, 
a question of nutrition. 
Parasitism of Orobanche.|| — Dr. G. Ritter Beck von Mannagetta 
gives the characters of the 13 genera of the order Orobancheae, and a 
complete monograph of the 82 species of Orobanche. With regard to their 
parasitism, he finds that, while a few species — 0. Laserpitii, Hederse, and 
Artemisise — are known only on a single host-plant, a much larger number 
grow on many indifferently, 0. minor on as many as 58 species. The 
natural orders to which the greatest number of the host-plants belong 
* Bull. Soc. Linn. Normandie, 1888-9 (1890) pp. 199-223 (1 pi.). 
f Verhandl. Bot. Yer. Brandenburg, xxx. (1889) pp. ii.-v. 
X Cf. this Journal, 1888, p. 992. 
§ Proc. Roy. Soc., xlvii. (1890) pp. 393-443 (1G figs.). 
|| Luerssen u. Haenlein’s Biblioth. Bot., Heft 19, 1890, 275 pp. and 4 pis. 
