ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
663 
subject from experiments. Each species lias its own optimum of con- 
ditions with respect to the composition of its substratum, and we are not 
at present in a position to lay down laws which hold good for all fungi. 
Calcium salts are certainly not essential as a general rule. 
Spore-Formation of Thamnidium.* * * § — From experiments made by 
Herr J. Bachmann, it is stated that Thamnidium elegans is the only 
fungus at present known which can be made, by alteration of the external 
conditions, to form different kinds of sporange, or to suppress their 
formation altogether. The different forms are classed under six types, 
viz.: — (1) Terminal sporanges, sporangioles with few spores ; (2) ter- 
minal sporanges, sporangioles with numerous spores and often with a 
columel ; (8) terminal sporanges only ; (4) sporangioles only ; (5) mycele 
with thick ends and gemmae, or with thin ends and no gemmae ; 
(6) zygospores. These forms occur according to the chemical constitu- 
tion of the nutritive substance, its concentration, its fluidity, the degree 
of moisture, or the temperature ; and the various conditions are given 
in detail. Thamnidium exhibits less heliotropism than Mucor. 
Exoascaceae. — From a further examination of the parasitic fungus 
which causes deformation of the carpels of the aspen, Herr R. Sadebeck f 
concludes that it belongs to the genus Exoascus and not to Taphrina , and 
he proposes to call it E. Johansonii. This establishes on Arm ground 
the distinction between the genera Exoascus and Taphrina. He now 
enumerates 30 species of Exoascus , 13 of Taphrina , and 6 of Magnusiella. 
Prof. G. F. Atkinson J describes thirteen species of Exoascus para- 
sitic on different species of Prunus in the United States, and causing 
curl or plum-pocket. The following are new : — E. confusus, on fruits 
and flowers of P. virginiana ; E. longipes , on fruits of P. americana ; 
E. mirabilis , on buds, shoots and fruits of several species ; E. rhizipes , 
on buds and fruits of P. trijiora ; E. decipiens, on leaves, shoots, and 
fruits of P. americana ; E. varius, on leaves and shoots of P. serotina ; 
E. cecidomophilus , on Cecidomya- galls on fruit of P. virginiana. 
Yeast- aud Mould-Fungi on Grapes.§ — From observations made 
during fermentation experiments, Dr. H. Eckenroth and Herr R. Hei- 
mann have come to the conclusion that mould-fungi undergo a peculiar 
metamorphosis on grapes. The grapes came from various parts of the 
Palatinate, almost all being covered with mould, and more or less 
sprinkled with Oidium Tuckeri. Microscopical examination showed 
that these grapes were coated with yeast-like cells. Cultivations were 
made from these cells on moist gelatin plates, and pale rose-coloured 
colonies, consisting of torula-like cells, grew up. These cells were in 
their turn cultivated in sterilised must in Freudenreich’s flasks, and 
developed a mycele consisting of a branched dematium-like vegetation. 
This increased considerably on continued cultivation, and sprouting cells 
and large swellings on the mycele appeared, while the terminal branches, 
* Bot. Ztg., liii. (1895) l te Abt., pp. 106-30 (1 pi.). 
t Ber. Deutsch. Bot. Gesell., xiii. (1895) pp. 265-80 (1 pi.). Cf. this Journal, 
1891, p. 487. 
X Cornell Univ. Agr. Exp. Stat., 1891, pp. 319-55 (20 pis.). See Bot. Centralbl., 
1895, Beih., p. 360. 
§ Centralbl. f. Bakteriol. u. Parasitenk., 2 te Abt., i. (1895) pp. 529-36 (6 figs.). 
