98 NOTES AND MEMORANDA. 
Botanical Work at Vienna. — Several important papers appear from 
the workers at the Physiological Institut of Vienna in the Viennese 
Journal of Botany. One of these is a memoir on the origin of hairs 
in the intercellular canals of the mesophyllum of the petioles of 
Philodendron pertusum. Another is on the crystals of oxalate of 
lime that one sees in the mesophyllum of the petioles of Pontedera 
crassipes. A third is upon the transpiration of the branches of 
^sculus hipjpocastanum^ of Taxus, &c. 
The Morphology of the Placenta in Plants. — This subject is worked 
out in an important memoir, published in the ' ActsB ' of the Eoyal 
Society of Prague (1875), by Professor Celakowsky. He arrives at 
the conclusion that the placenta is always a carpellary product, and 
that it varies only in its points of formation upon the ovary. 
The Relations of Algce and Fungi. — The ' Revue des Sciences 
Naturelles ' * states that in the ' Journal des Sciences Naturelles de 
Pisa ' (fasc. ii.) is published a valuable paper on this subject, by 
Professor Archangeli. He asks the question whether the gonidia are 
produced by the frond of lichens (Tulasne's and Nylander's ideas), or 
are, on the contrary, of an external growth {provenance exterieure) 
(Swendener's view). Accepting the latter idea, he says that the 
gonidia would form Algas, and the lichens would become Discomy- 
cetous Fungi living upon these Algae. Professor Archangeli dis- 
cusses both of these views, but he adheres to the former. 
The Sexual Organs of Fungi. — At the late Congress of Gratz, 
Herr Dr. Eidam related his observations on the sexual organs of 
Hymenomycetous Fungi. He traced out the development of the 
male organs of Agaricus coprophilus. 
Parasitic Fungi. — In last year's volume of the ' Comptes Eendus ' 
of tbe Academy of Sciences of Naples is a memoir of Professor 
Cesati dealing with this subject. He treats of Puccinea malvacearum, 
a fungus which does immense damage to the culture of the Malva 
rosea in Bavaria. He also deals with a fungus which produces certain 
diseases of potatoes, and which is named Bhizoctoma tuhifera. 
NOTES AND MEMOKANDA. 
A Mode of Centering Mounts. — Dr. Christopher Johnston, of Bal- 
timore, U.S.A., in a short note addressed to us on June 13, suggests 
the following simple plan for making mounts well centered. After 
cleaning a slide, choose the better surface for the object. Centre the 
slide upon a turn-table, with the better side down, rotate the table, and 
at the same time trace with a pen a circle in ink. This dries in a 
moment, is an easy guide to the preparer, and can readily be washed 
off, whatever treatment the slide may receive. 
* T. iv. No. i, 1876. 
