444 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Strepsithalia, a new Genus of Phaeosporese.* * * § — M. C. Sauvageau 
finds endophytic on Helminthocladia and other marine algae, two species 
of this genus of Ectocarpaceae, which presents points of resemblance 
with Elachistea, Streblonema , and Myrionemn. The following is the 
diagnosis of the genus : — Thallus maculiformis endophyticus, e filis 
articulatis monosiphoniis muco gelatinoso vaginatis formatus ; fila 
primaria horizontalia, incremento indefinito intra cellulas plant® 
matricalis excurrentia, ramosa, hinc inde fila secundaria erecte definita, 
clavata v. cylindrica, simplicia, aut basi bis terve furcata, in pulvinulos 
minutos densos congregata emittentia ; pili ad modum Phseosporearum 
confecti e filis repentibus et a basi filorum verticalium provenientes ; 
sporangia utriusque generis e cellulis inferiorum filorum nascentia ; 
unilocularia ovoidea v. piriformia, plurilocularia filiformia, cylindrica, 
loculis uniseriatis. 
Production of Azygospores in Zygnema.f — According to Fraul. E. 
Hallas, a species of Zygnema is frequent in the neighbourhood of 
Copenhagen, which forms bodies resembling zygosperms without any 
previous process of conjugation. Their production is preceded by an 
increase in the number of chromatophores ; the protoplasm then con- 
tracts into a spherical mass, and becomes clothed with a coat of cellulose. 
After about 2 J months, the spore begins to germinate within the mother- 
cell. 
Chlamydomonas grandis and Kleinii.J^ — Herr W. Schmidle dis- 
sents from Dill’s proposal to identify these two species. He points out 
that the latter species is readily distinguished, among other characters, 
by the invariable presence of only two pyrenoids, and by the division 
taking place not longitudinally, but transversely. G. grandis is a 
“ collective species,” the forms included under it differing in the presence 
or absence of longitudinal bands, in the presence or absence of a beak 
through which the cilia project, and in the presence or absence of proto- 
plasmic warts. 
Calcareous Pebbles formed by Algae. §— Prof. D. P. Penhallow has 
subjected the calcareous pebbles from Michigan to a more detailed 
examination, and finds that, in addition to the ScJiizothrix fasciculata and 
numerous diatoms, they contain fragments of (Edogonium, Glceocystis , 
Calothrix, and Urococcus , and especially plants of Sirosiphon informe , and 
large quantities of Dicothrix gypsophila. The specific composition of the 
pebbles appears, however, to vary according to circumstances. 
Aquatic Forms of Stiehococcus.|] — Herr J. af Klercker has culti- 
vated two aquatic forms of Stichococcus , which he names S. subtilis and 
bacillaris , and gives a synopsis of the characters of the known species of 
the genus. These -two species are both characterised by the presence 
in the cells of large numbers of “ spherules ” of an oily substance, 
especially where the rapidity of the cell-division is repressed by a large 
proportion of magnesium and iron in the nutrient solution. External 
* Journ. de Bot. (Morot), x. (1896) pp. 53-65 (8 figs.). 
t Bot. Tidssk., xx. (1895) pp. 15-6 (2 pis.). See Bot. Centralbl., lxvi. (1896) 
p. 223. % Flora, lxxxii. (1896) pp. 85-9 (6 figs.). Cf. this Journal, ante, p. 213. 
§ Bot. Gazette, xxi. (1896) pp. 215-7. Cf. this Journal, ante, p. 91. 
|| Flora, lxxxii. (1896) pp. 90-106 (1 pi.). 
