ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
657 
cent., from saccharine solutions. Mucor pyriformis produces a larger pro- 
portion of citric acid when grown on boiled rice, developing at the same 
time an ethereal odour. With both fungi, however, the production of 
citric acid is uncertain. 
Calcium oxalate in Fungi.* — Mr. C. B. Plowright records the 
occurrence of crystals of calcium oxalate in the lamellm of Clitocybe 
cyathiformis ; also in Geaster mammosus, where they have a regular 
octahedral form. 
Development of Sporodinia grandis.f — Herr G. Klebs finds this 
species a specially favourable one for observing the influence of external 
conditions on the reproduction of Fungi, since it produces readily both 
zygotes and sporanges, and is easy to cultivate in nutrient solutions of 
very different composition. It is not, as has been stated, a parasite, but 
a saprophyte. Herr Klebs finds the production of sexual or non-sexual 
organs of reproduction not to be due, as van Tieghem has stated, to the 
presence or absence of oxygen, but to the degree of moisture of the air. 
If the air is comparatively dry, i.e. if the conditions are favourable for 
active transpiration, the aerial hyphse produce sporanges. If, on the 
other hand, the air is moist and the transpiration checked, zygotes are 
produced. Temperature and light play only a secondary part, as they 
affect moisture and transpiration. The formation of parthenospores 
can be induced in a variety of ways, as by a diminution of the air 
pressure. 
Structure of the Peronosporacese4 — A study by Prof. A. N. Berlese 
of the vegetative organs of the Peronosporacese ( Peronospora , Phyto- 
phthora, Plasmopara , Cystopus, &c.) leads him to the following general 
conclusions. The mycele is furnished with true haustoria for absorbing 
the nutriment from the host-plant ; their form differs in the different 
genera. The presence of callose in the cell- walls is confirmed. Distinct 
conidiopliores do not occur in all the genera ; in Pythium the filaments 
which bear the conids or the zoosporanges differ in no respect from the 
ordinary filaments of the mycele ; they present the strongest differ- 
entiation in Basidiophora, Plasmopara , and Peronospora ; in Phytoplithora 
they are occasionally branched. The conids are solitary, except in Cys- 
topus and in some species of Pythium ; they are often papillose. They 
are multinuclcate, the number of nuclei usually varying between 4 and 
8 ; they have been derived directly from the conidiophore. Besides the 
conids, which produce zoospores on germinating, Pythium possesses a 
second kind of zoosporange, often borne on special branches of the 
mycele. 
Division of the Nucleus and Formation of the Conids in Oiclium.§ 
— Prof. A. N. Berlese has studied these phenomena especially in 0. moni- 
lioides, parasitic on grasses, the imperfect form of Erysiphe graminis. The 
division of the nucleus is karyokinetic, and presents all the usual stages. 
The conids are not formed successively one at a time, as stated by de 
Bary. The cylindrical cells, rich in granular protoplasm, near the apex 
* Bull. Soc. Mycol. de France, 1898, p. 13 (2 pis.). 8ee Bot. Centralbl., 1898, 
Beih., p. 42. 
t Jahrb. f. wiss. Bot. (Pfeffer u. Strasbuvger), xxxii. (1898) pp. 1-70 (2 figs.). 
X Riv. di Patol. Veg., vi. (1897) pp. 78-101, 237-68. Of. this Journal, ante , 
p. 455. § Tom. cit., pp. 6G-75 (2 pis.). 
2 Y 2 
