ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
785 
process of cell-division. The cells contain small oval chloroplasts ; 
multiplication takes place by means of zoospores, only one of which is 
formed in each mother-cell. 
The Idea of Species in Diatoms.* — M. J. Deby replies to the paper 
by Dr. J. D. Cox, in which that authority proposes a great reduction 
in the number of genera and species of diatoms, and points out that 
the transitory forms of Cox are the same things as the species of those 
who accept the hypothesis of evolution. 
Diatoms of France. f — Messrs. J. Tempere and H. Peragallo have 
issued thirty-one parts of a series of preparations of the diatoms of 
France, named by M. Peragallo. Each part contains twelve species. 
New Genera of Diatoms. J — M. J. Brun describes a number of new 
species of marine, pelagic, and fossil diatoms, from various parts of the 
world, together with the two following new genera : — Cotyledon , dis- 
tinguished by the valve being more or less circular, and bearing an 
elevated irregularly folded crest ; the position of the genus is at present 
uncertain. Hydrosilicon , characterized by a lamellar, sometimes pan- 
duriform, valve, having a pseudo-raphe with simple or double bifurca- 
tions towards the extremity of the valve ; the margin is thickened and 
covered by a row of large pearls ; the striations have for their centres 
of radiation axes crossing the raphe. 
Under the name Streptotheca Tamesis, Mr. W. H. Shrubsole § 
describes what he regards as a new form of diatom from the estuary of 
the Thames, where it has appeared every autumn and winter for several 
years. It has the form of a flattish band, slightly twisted in the 
direction of its length, so as to form an open spiral. It is extremely 
delicate and transparent, but is rendered visible by splashes of bright 
colour. It is almost entirely destitute of silica. 
Monograph of Pleurosigma. || — M. H. Peragallo has published a 
monograph of the genus Pleurosigma and its allies. These latter he 
classes nnder three genera, viz. Bho'icosigma , Donhinia, and Toxonidea. 
The genus Pleurosigma properly so-called is divided into eleven groups, 
viz. Formosi, Speciosi, Affines, Angulati, Rigidi, Attenuati, Acuminati, 
Strigiles, Colletonema, Fasciolati, and Staurosigma. 
Auliscus.^f — M. J. Deby gives a catalogue of all the known species 
of Auliscus, including Pseudauliscus, about 120 in number. 
B. Schizomycetes. 
Phagocytosis.**— At the International Congress of Hygiene a valu- 
able discussion was held on this subject. Dr. Roux, of the Institut 
Pasteur, in an introductory address, indicated the scope of the discussion. 
He began by saying that, in inviting a pupil of M. Pasteur to open the 
* Journ. de Microgr., xv. (1891) pp. 112-4, Cf. this Journal, ante , p. 385. 
t ‘ Les Diatomes de France,’ Ser. I -XXXI. Paris, 1890. See Bot. Centralbl. 
xlvii. (1891) p. 12. 
X Mem. Soc. Phys. Geneve, xxxi. pt. 2 (1891) (48 pp. and 12 pis.). 
§ Journ. Quek. Micr. Club, iv. (1891) pp. 259-62 (1 pi.). 
|| ‘ Monographie du genre Pleurosigma et d. genres allies,’ Paris, 1891, 35 pp. and 
10 pis. f Journ. de Microgr., xv. (1891) pp. 183-9. 
** Nature, xliv. (1891) pp. 419-23. 
