ZOOLOGY AND BOTANY, MICBOSCOPY, ETC. 
371 
The Acrasiese comprise the genera Copromyxa, Guttulina, Dictyo- 
sielium, Acrasis, and Polysphondylium ; the Phytomyxineas, Plasmodio- 
phora, Phytomyxa, Tetramyxa, and Sorosphsera. The numerous genera 
of Myxogastres or true Myxomycetes are divided into 11 families. 
Pseudospora.* * * § — Prof. C. Gobi describes the structure and develop- 
ment of this parasite on living Vauclierise. The motile naked masses of 
protoplasm develope a single cilium at the posterior end, and must then 
be regarded as zoogonids, and their mother-cells as zoocarps or zoo- 
sporanges. The zoogonids consume the protoplasm and the chlorophyll 
of the host; when mature, they multiply by repeated bipartition. 
Finally they become encysted into zoocarps, which may either reproduce 
zoogonids directly, or plasmamoebsB in the first place, of the form which 
the author calls actinophryds, globes with radially arranged pseudopods ; 
these are reproduced in several ways. Both the zoogonids and the 
actinophryds can pierce the wall of the Vaucheria-sac, and, after they 
have moved about it for a time, transfer themselves to another one. The 
author traces a resemblance between the development of Pseudospora 
and that of Plasmodium Malarise. 
Protophyta. 
o. Schizophyceee. 
Auxospores of Chaetoceros.t — Herr F. Schfitt describes the mode of 
formation of the auxospores in this marine genus of diatoms. In a cell 
in the chain which has attained its maximum length, the valve is 
perforated at a spot on its girdle-band, and the protoplasm protrudes 
as a small vesicle, and becomes invested by a fine shell, the entire 
protoplasm of the mother-cell finally passing into it. The nearly 
globular auxospore attains double or three times the diameter of the 
mother-cell, and then somewhat increases in length in the diameter at 
right angles to the axis of the mother-cell. The protoplasm then con- 
tracts, and becomes invested in a new siliceous coat, which gradually 
assumes the form characteristic of the genus, while the horns are at the 
same time gradually formed out of the surface of the valve, and break 
through the siliceous coat ; the new cell, which is placed at right angles 
to the original chain, and is much larger than its component cells, now 
divides transversely. 
Fossil Diatoms of Gianicolo.J — Dr. M. Lanzi describes the dia- 
tomiferous deposit found near the summit of Monte Gianicolo, within 
the Roman basin, with a list of the species. 
Cells of the Cyanophyce8e.§ — Herr E. Zacharias has carefully ex- 
amined the structure of the cell in the following genera of Cyanophycese, 
viz.; — Oscillaria, Nostoc, Cylindrospermum^ Tolypothrix, and Scytonema. 
He finds in all cases, in the living cell, a central colourless portion, 
surrounded by a peripheral layer of protoplasm, in which alone the 
* Ber. Gesell. off. Gesundheitspflcge, Petersburg,, 1887 (Russian). See Bet. 
Centralbl., xxxix. (1889) p. 346. 
t Ber. Deutsch. Bot. Gesell., vii. (1889) pp. 361-3 (1 pi.). 
X Atti Accad. Pontif. Nuov. Lincei, xlii. (1889) 9 pp. 
§ Ber. Deutsch. Bot. Gesell., vii. (1889) Gen.-Versamml.-Heft, pp. 31-4, aud 
Bot. Ztg., xlviii. (1890) pp. 1-10, 17 26, .33-43, 49-60, 65-70 (1 pi.). 
2 D 2 
