490 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
plies by repeated division. Another new genus and species belonging 
to the same family is Placosphsera opaca , consisting of spherical or 
somewhat elliptical cells 24 p in diameter, with a thick calcareously 
incrusted membrane, a central pyrenoid, and lateral nucleus. It is 
reproduced by repeated division, and appears to be most nearly allied to 
Nephrocytium. 
The author regards the Hydrodictyese as derived from the Yolvocinefe, 
the colonies having lost their motility ; under unfavourable vital con- 
ditions they may become encysted. Polyedrium trigonum Nag. is not a 
stage in the development of a Pediastrum , but is an independent 
organism ; it breaks up, on germination, into new individuals. This 
genus and Scenedesmus may be considered as abnormal Hydrodictyese, 
in which the production of zoospores and sexual reproduction are 
suppressed. 
Hybrid Desmid.* * * § — Mr. A. W. Bennett describes a possible hybrid 
desmid between Euastrum humerosum and E. crassum. 
Trentepohlia.j — M. E. de Wildeman recurs to several critical points 
in determination of the species of this genus, and dissents from its 
division into two classes by De Toni and Hansgirg, dependent on the 
colour and odour, characters which vary with the conditions of growth 
ai d of drying. Species, he states, which have been separated and 
placed in the two classes ought to be united. He proposes an alternative 
classification into two groups, the first with the cells cylindrical, or 
rarely irregularly elliptical, the second with the cells oval, elliptical, or 
irregular, never cylindrical. The species in both groups vary as to 
colour and odour. 
M. P. Hariot J gives a complete monograph of the genus, which he 
considers as nearly allied to Cladophora, differing in its terrestrial 
habit, its more or less bright coloration, and its mode of fructification. 
The family Trentepohliacese is divided by him into two groups, Cepha- 
leuroidece and Chroolepideaa, the latter being made up of the two genera 
Trentepohlia and Nylandra. He classifies the species of Eu-trentepohlia 
under two groups, the first with cylindrical cells (11 species), the second 
with torulose or moniliform cells (6 species). One new species is 
described. T. Wainoi. A second sub-genus, Heterothallus, intermediate 
between Eu-trentepohlia and the Phycopeltidese, has the primary filaments 
ramifying in a single plane, and forming a circular horizontal rosette. 
It comprises three species, including T. depressa, hitherto included under 
Ccenogonium , and a new species, T. Leprieurii, from Cayenne. 
The new genus Nylandra , comprising only a single species, N. tenta- 
culata , is distinguished from Trentepohlia only by the cells of the thallus 
producing setiform appendages. 
Movements of the Protoplasm in Caulerpa.§ — Dr. J. M. Janse has 
investigated the nature of the energetic movements of protoplasm within 
* Ann. of Bot., iv. (1889) pp. 171-2 (1 fig.). 
t Bull. Soc. R. Bot. Belgique, xxviii. (1889), Pt. ii., pp. 67-70, 95-100, 125-7. 
Cf. this Journal, 1889, p. 420. 
t Journ. de Bot. (Morot), iii. (1889) pp. 345-50, 366-75, 378-88, 393-405 ; iv. 
(1890) pp. 50-3, 85-92, 178-80, 192-7 (24 figs.). 
§ Jahrb. f. Wiss. Bot. (Pringsheim), xxi. (1889) pp. 163-284 (3 pis. and 1 fig.). 
