ZOOLOGY AND BOTANY. MICROSCOPY, ETC. 363 
establish a new class of Xanthophyceas, parallel with the Phceophycea) 
and Cyanophyceae, to comprise Hydrurus , Naegeliella , Pliseothamnion , and 
Chromophyton , with which the Diatomacete are closely allied, character- 
ized by containing diatomin. 
Myriotrichia.* — Mdlle. N. Karsakoff describes in detail the structure 
of two species of this genus of Plneosporeae, M. clavseformis and filiformis, 
especially the mode of escape and conjugation of the zoospores. The 
zoosporanges are of two kinds ; in M. filiformis the plurilocular contain 
from 4 to 12 zoospores, in 31. clavseformis from 8 to 32. The zoospores 
may escape by either one or two openings. Conjugation was observed to 
take place only among the zoospores from the plurilocular sporanges, 
and never between two from the same sporange. The two conjugating 
zoospores (gametes) were always of unequal size, the smaller one be- 
coming absorbed in the latter. Conjugation takes place either when 
the zoospores are still in the motile, or when they are passing into the 
immotile condition. Hauck’s genus Dichosporangium must be sunk in 
Myriotrichia . 
Chlorophyll-bodies of Lesmidiacese-f — Dr. J. Liitkemiiller disputes 
the validity of the character drawn from the number and arrangement 
of the pyrenoids for determining the generic characters of desmids. 
It is generally given as a character of Cosmarium that the number of 
pyrenoids in each half is always the same, either 1 or 2, and constant in 
the same species. Dr. Lutkemiiller found, on the other hand, a large 
number of specimens of C. pyramidatum with 3, 4, or 5 pyrenoids in 
each half-cell, and frequently a different number in each half. C. 
pseudo-protuberans, which normally has 1 pyrenoid in each half-cell, 
was found occasionally with 2 or 3 in one or both. The specific dif- 
ference between C. botrytis and C. pseudo-botrytis founded on the number 
of pyrenoids is not constant. G. speciosum has occasionally 2 in each 
half-cell. A similar variability in the number of pyrenoids was found 
in Arthrodesmus corner gens and Staurastrum echinatum. 
In Docidium baculum individuals occur with parietal instead of 
central chlorophores, thus breaking down the distinction between that 
genus and Pleurotsenium. 
The author states that in Pleurotseniopsis tessellata each chlorophore 
consists of two layers, one of which is disc-shaped and contains the 
pyrenoid, while the outer layer consists of ribbon-shaped prolongations, 
which are directed towards the warts on the surface, ending in them. 
In P. de Baryi, the surface of which is not warty, the chlorophores 
have a similar structure, and the same is the case with P. turgida. 
Fungi. 
Classification of Fungi. :£ — Herr F. von Tavel gives a resume of the 
relationships of the various families of Fungi, according to the system of 
Brefeld. He regards the Fungi as being derived from the Alga 3 , the 
families most nearly allied to the latter being the Peronosporese and 
* Journ. de Bot. (Morot), vi. (1892) pp. 433-44 (1 pi. and 2 figs.). 
t Oesterr. Bot. Zeitschr., xliii. (1893) pp. 5-11, 41-4 (2 pis.). 
j ‘ Das System d. Pilze,’ Zurich, 1892, 15 pp. and 1 fig. See Bot. Centralbl., lii. 
(J892) p. 9. 
