226 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
large size, and is differentiated into primary and secondary axes, and 
branched leaves. 
New Genera of Algae.* — In his monograph of the Algae of South 
Georgia, Dr. P. F. Keinsch describes four new genera, one freshwater and 
three marine, viz .-.—Dennatomeris, belonging to the Ulvaceae, with a 
coriaceous-gelatinous thallus; Stegastrum, belonging to the Chordari- 
aceae, and near to Myrionema , epiphytic on Porphyra ; Melastictis , 
doubtfully placed among the Chordariaceae, a true parasite ; and Bydru- 
rites , probably allied to Hydrurus. In none of them were the organs of 
reproduction made out with certainty. 
Conjugation of Spirogyra.f— According to Prof. G. Haberlandt the 
two corresponding conjugation tubes do not begin to be formed at the 
same time in Spirogyra quinina ; it is sometimes the tube of the male 
cell, sometimes that of the female cell, that is first formed ; and the 
place of formation of the later one is in all probability determined by 
the chemical excitation exerted by a substance exuded from the apex of 
the older tube. As the two tubes are not always formed exactly opposite 
to one another, one or the other has to bend in order that they may 
meet, and this curvature is also probably of a chemotropic character. 
The contraction of the protoplast of the female cell, and its conversion 
into a gamete are also the result of a direct excitation by the male cell. 
Trentepohlia.J — M. E. de Wildeman describes the species of Trente- 
pohlia natives of the Dutch East Indies, including the following new 
species : — T. Bossei, T. luteo-fusca, T. procumbens. The classification of 
the species is that adopted in his previous papers. 
Enteromorpha.§ — M. E. de "VTildeman has followed out the mode of 
growth of Enterornorpha intesiinalis, and especially the formation of the 
branches. In addition to the larger branches which spring from the 
base of the plant, there are often a large number of small branches 
springing from its upper region. Each of these originates in a rounded 
cell larger than those which surround it, which divides by a succession 
of transverse divisions to form a row of cells, and these finally, at least 
in the apical portion, also divide longitudinally. These branches may 
then become detached, and grow into new plants. 
Volvox and Eudorina.|] — Continuing his observations on Yolvox , 
Dr. L. Klein states that the colonies of V. globator are exclusively non- 
sexual and monoecious (almost invariably proterogynous), while in 
V. aureus as many as twenty-oue different combinations are possible, 
and actually exist. The oospheres, which can be distinguished with 
certainty from the parthenogonids only by their deeper colour before 
maturity, may, in certain cases, develope into daughter-colonies without 
impregnation. The author distinguishes two kinds of “ Sphserosira- 
form ” of V. aureus — the normal form in which the division of the 
* ‘Die Deutschen Polarexpeditionen,’ vi. (1890) pp. 329-449 (19 pis.). See 
Hedwigia. xxix. (1890) p. 285. 
f SB. K. Akad. Wiss. Wien, xcix. (1890) pp. 390-400 (1 pi.). 
X Ann. Jard. Bot. Buitenzorg, ix. (1890) pp. 124-42 (3 pis.). Cf. this Journal, 
1890, p. 490. § Xotarisia, v. (1890) pp. 1115-21 (1 pi.). 
Ber. Xaturf. Gesell Freiburg, v. (1890) 92 pp. and 5 pis. See Bot. Centralbl., 
xliv. (1890) p. 319. Cf. this Journal, 1889, p. 558. 
