ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
487 
(Sporodinia grandis , Mucor Mucedo , ill. racemosus, &c.) ; their structure 
does not differ essentially from that in the Saprolegniaceae, Ustilagineae, 
and Uredineae. Each nucleus has a nuclear membrane, separated from 
a central nucleole by cytoplasm, which is uncolourablo, or contains but 
little chromatin ; the nucleole is very dense, and is strongly stained by 
colouring reagents. The zygosperm contains a considerable number of 
nuclei, the nucleole of which is coloured red, while the protoplasm re- 
mains violet. There are a considerable number of nuclei in the mycele, 
in the clilamydospores, and in the budding spores ; the spores otherwise 
only contain one, or rarely two. The two gametes contain a number 
of nuclei, which are derived from the thallus. 
Structure of the Ustilagineae.* — M. P. A. Dangeard describes in 
detail the structure of the following species of Ustilagineae, — Ustilago 
Tragopogonis , U. carbo , U. violacea, Docissansia Alismatis, Entyloma 
Glaucii , Urocystis Violse , Tilletia caries. The structure of the mycele 
and the mode of germination of the spores present peculiarities in each 
case. Various processes previously described as sexual in Eurotium and 
Tilletia have not that character ; the true sexual process consists in the 
fusion of nuclei within the ascus. The author accepts Frank’s union of 
the Ustilagineae and Uredineae into a class of Mesomyoetes, representing 
an intermediate stage of evolution between the Phycomycetes on the 
one hand, and the Basidiomycetes and Ascomycetes on the other hand. 
The so-called spores of the Ustilagineae, and the teleutospores of the 
Uredineae are homologous to oogones. 
Ustilago producing Woody Tumours.f — Under the name Ustilago 
Vriesiana M. P. Vuillemin describes a new species which forms woody 
tubers in various species of Eucalyptus , resembling the well-known 
“ chaudron ” of the spruce fir. This is the first time that such a 
property has been observed in any species of Ustilago. The structure 
of the parasite is described, and that of the tumour in detail. The 
latter consists of a woody structure penetrated by fine canals, and with 
irregular intercellular spaces. The local lesion produced by the 
parasite is more fatal to the fungus itself than it is to the host. 
Exoascese.f — Ur. R. Sadebeck gives a monograph of the parasitic 
Exoasceae, comprising the three genera Exoascus (21 sp.), Taphrina (15 sp., 
including Taphrinopsis), and Magnusiella (5 sp.). To the same family 
belong also the following saprophytic genera, — Eremascus , Ascodermis, 
Podocapsa , Oleina , Eremothecium , Bargellinia , Endomyces , and Ascocor- 
ticium. 
Structure of Lichens.§ — M. P. A. Dangeard brings forward several 
points in the structure of lichens which confirm Schwendener’s theory. 
In the algal constituent, the body which has hitherto been taken for 
a nucleus is in reality a pyrenoid ; the true nucleus, which is nucleolated, 
is situated beneath the membrane, and has been described as a vacuole. 
By the use of the proper reagents, the protoplasm can be stained yellow, 
* Le Botaniste (Dangeard), iii. (1894) pp. 240-81 (4 pis.). 
+ Comptes Rendus, cxviii. (1894) pp. 933-6. 
X Jahrb. Hamburg Wiss. Anstalt, 1893, 110 pp. and 3 pis. See Bot. Centralbl- 
Ivii. (1894) p. 334. Of. this Journal, 1886, p. 489. 
§ Comptes Rendus, cxviii. (1894) pp. 931-2. 
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