ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
79 
gigantea. An instance is noted of Polyporus ulmarius, not usually 
described as parasitic, attaining a gigantic size, and causing evident 
pathological effects, on an elm-tree. 
Parasites on Algae.* * * § — M. P. A. Dangeard describes the following 
fungi parasitic on various algae : — 
Olpidium aggregatum sp. n. on a marine Cladophora, allied to 0. 
Bryopsidis. 
Chytridium mamillatum, on Draparnaldia glomerata ; C. a&ymmetricum 
sp. n. on Conferva bombycina ; C. ( Bhizidium ) sphserocarpum, on a 
Zygnema. 
Micromyces Zygogonii on a Zygogonium. This is referred to the 
Synchytrieae. 
Bacillus Closterii sp. n., on several Closteria. 
A number of parasites on algas are also described belonging to the 
animal kingdom. 
Fungus-vegetation on Snow.f — M. Worouin finds that in Finland 
*the snow is often covered, when it begins to melt in the spring, with 
fungus-mycele, derived largely from the excreta of animals, and de- 
veloping into a Mucor. Where the snow has more completely dis- 
appeared, a different mycele is found, which developes into small 
sclerotes resembling those of Penicillium. This takes place even when 
the temperature falls every day below the freezing-point. 
Sphaerella gossypina sp. n.J — Prof. G. F. Atkinson claims to have 
discovered the perfect stage of Cercospora gossypina, a very destructive 
parasite on the cotton-plant, in a Sphaerella which he finds on both 
sides of the leaves of the same plant. 
Dimorphism of Hypocrea tuberiformis.§— Prof. G. F. Atkinson 
describes the two forms of this fungus parasitic on Arundinaria , — 
the sphacelia stage found in May, and the ascigerous stage in August 
and September. The author claims to have established the affinity of 
the genus with Epichloe, the only difference being that in the latter 
genus the stroma entirely surrounds the stem of the host ; while in 
Hypocrella (in which Hypocrea should be sunk) the mature stroma 
only partially surrounds the stem or is borne on the under-side of the 
leaf or leaf-sheath. 
Conidiferous Apparatus of Meliola.|| — M. A. Gaillard states that the 
conidiferous mycele of Meliola draws its origin from the same spore 
as the peritheciferous mycele. The conids arise on simple ramifica- 
tions of the conidiferous mycele or on simple or compound conidiferous 
threads. The denomination conidiferous threads ought to be reserved 
for those which issue from the conidiferous mycele ; the threads of the 
peritheciferous mycele never produce conids, and are sterile branches 
of this mycele. 
* Le Botaniste (Dangeard), ii. (1891) pp. 231-68 (4 pis.). 
f Arb. St. Petersb. Naturf.-Ver. (Bot.), xx. p. 31. See Bot. Centralbl., xlvii. 
(1891) p. 302. 
1 Bull. Torrey Bet. Club, xviii. (1891) pp. 300-1 (1 pi.). 
§ Bot. Gazette, xvi. (1891) pp. 282-5 (1 pi.). 
|| Rev. Mycol., xiii. (1891) pp. 174-7. 
