ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
109 
and fifty striations going round the valves. The connection attaching 
the valves is rounded or slightly oval, and is apparently perforated 
axially by two D-shaped apertures, but occasionally a single oval 
opening traverses the collar ; or, again, the cross-piece separating the 
D-openings appears incomplete, and is represented by projections ex- 
tending into an oval opening. 
De Toni’s Sylloge Algarum.* * * § — The fourth volume of this most 
valuable work commences the enumeration of the Florideae. These are 
first divided into the two sub-classes, the Bangioideae and the Euflorideae. 
The first includes, besides the Baugiacere, the monotypic family Rhodo 
chaetaceae, and doubtfully the Compsogoniaceae and the Thoreaceae. The 
Euflorideae are divided into four orders, — the Nemalioninae, Gigartininae 
Rhodymeninae, and Cryptoneminae. Of these the first is fully treated, 
with its four families, the Lemaneaceae, Helminthocladiaceae, Chaetan- 
giaceae, and Gelidiaceae. The Gigartininae comprise three families, — the 
Acrotylaceae, Gigartinaceae, and Rhodophyllidaceae, which are also com- 
prised within the volume. A most copious bibliography is appended. 
Fungi. 
Nuclear Division among Fungi. — Mr. R. A. Harper j has studied 
the processes of division of the nucleus and free-cell-l'ormation in the 
ascus of Erisyphe communis , and points out the close resemblance to the 
similar processes observed by several authorities in animals. Through- 
out the whole process the nucleus is accompanied by a centrosphere. 
At the commencement of the formation of the spindle the chromatin is 
collected into a dense net round the centrosphere, with which it appears 
to be closely connected ; the chromosomes are united with the centro- 
sphere by cytoplasmic threads. When the true formation of spores 
commences, the apex of the nucleus is gradually drawn out into a beak. 
The boundary wall of the young ascospore is composed of the same 
kinoplasmic substance as the polar radiations and spindle fibres. The 
true wall of the spore, composed of cellulose, is only formed at a later 
period. 
Mr. D. G. Fairchild J has investigated the phenomena of nuclear 
division and impregnation in Basidiobolus ranarum. The chromo- 
somes form a broad equatorial plate in a short barrel-shaped nearly 
cylindrical spindle. During division the wall of the nucleus appears 
to remain unchanged. In the process of conjugation the two nuclei 
fuse completely during the formation of the zygosperm. In the de- 
velopment from conids to zygosperms, we have probably the most rapid 
alternation of sexual and non-sexual modes of multiplication known 
in the vegetable kingdom. 
Action of Gravity on the Growth of Fungi.§ — By direct observa- 
tion on Sterigmatocystis alba, M. J. Ray has determined that gravitation 
has a retarding effect on the growth of the lower fungi. 
* Vol. iv., Patavii, 1897, lxi. and 388 pp. 
f Jahrb. f. wiss. Bot. (Pfeffer u. Strasburger), xxx. (1897) pp. 249-81 (2 pis.). 
j Tom. cit., pp. 285-96 (2 pis.). 
§ Comptcs Rendus, cxxv. (1897) pp. 500-1. 
