ZOOLOGY AND BOTANY, AIICKOSCOPY, ETC. 383 
may be distinguished from a biological point of view, the free and the 
stalked ; the latter are chiefly PseudorapliideaB, and form, both bio- 
logically and morphologically, a connecting link between the other two. 
The Raphideaj or Euraphidese are the most highly developed type ; the 
formation of auxosporcs is often preceded by the apparently sexual union 
of two cells ; in the Arapliidese or plancton-forms, on the other hand, 
the auxospore is the product of a single mother-cell, as in Chsetoceras 
and Bhizosolenia. A similar process is now described for the first time 
in Sceletonema costatum. Although not without exception, the arrange- 
ment of the chromatophores is usually more or less uniform in the 
species of a genus, and even in nearly related genera. 
Protoplasts ,of the Cyanophycese.* — Herr E. Palla has examined 
the structure of a number of species of Cyanophycese — Gloeotrichia 
Pisum, Tolypotlirix lanata , Sphserozyga oscillarioides, Anabsena Azollse, 
Nostoc humifusum , Oscillaria sp., Lyngbya papyrina , Chroococcus turgidus , 
Gloeocapsa sp., and the gonids of Peltigera canina — with the view of 
determining the nature of the central body. The protoplast contains 
uniformly a colourless and apparently homogeneous central portion, 
which divides by constriction and is stained by methyl-blue in the 
living state. The chromatophore has apparently a reticulate structure, 
and is separated from the central body by a colourless layer of proto- 
plasm. The cells contain large vacuoles ; and outside the central body 
are granular structures of two kinds — cyanophycin-granules and muci- 
lage-globules. The cyanophycin-granules are apparently solid, and are 
usually found in the outermost portion of the chromatophore. The 
mucilage-globules are generally situated close to the central body ; they 
are identical with the so-called nucleoles. When the spores of Gloeotrichia 
germinate an oil makes its appearance in the cells. 
The central body differs, according to Palla, in several important 
points from a true nucleus, — in the absence of a chromatin-framework 
and of nucleoles, and in its direct mode of division, which has nothing 
in common with the process of karyokinesis. If the central body is not 
a true nucleus, it follows that the Cyanophyceae (and the Schizomycetes) 
are not a degraded type descended from higher organisms, but are an 
archaic type standing at the base of both the animal and the vegetable 
kingdoms. 
Herr H. Zukal f believes one of the principal functions of the cyano- 
phycin-granules to be the excretion of that substance. It is in these 
granules that cyanophycin, oil, and a red pigment are stored up. When 
the cyanophycin is expelled, it takes either a crystalline form or that of 
minute drops in the cytoplasm. These are frequently transformed into 
mucilage-globules, or into the “central mass” of authors, when they 
assume a great resemblance to a cell-nucleus. 
/ 3 . Schizomycetes. 
Action of Ozone on Micro-organisms.^ — Sig. G. Tolomei states, from 
observations made chiefly on Saccharomyces ellipsoideus and cerevisise and 
* Jahrb. f. wiss. Bot. (Pringsheim), xxv. (1893) pp. 511— B2 (2 pis.). ; and Ber. 
Deutsch. Bot. Gesell., xi. (1893) pp. 394-5. Cf. this Journal, 1892, p. 655. 
f Ber. Deutsch. Bot. Gesell., xii. (1894) pp. 49-52. 
X Atti K. Accad. Lincei, ii. (1893) pp. 354-61. 
