280 SUMMARY OF CURRENT RESEARCHES RELATING TO 



rich in organic nutriment. For several weeks Gonium pectorals formed 

 a water-bloom in which 300-400 colonies were present in 1 c.cm. of 

 water. Pandorina mo ram and Sivnalrsmus <]aa<lricnuda also occurred. 

 Towards the end of November isolated growths of Evglena rim/is were 

 found, and Gonium was duly present in dividing colonies. Pandorina 

 and Scenedexmas disappeared almost entirely. The author quotes publi- 

 cations by various authors to support his view that many Volvocaceae 

 ate ready on certain occasions to absorborganic nutrition, and to develop 

 luxuriantly. 



Brandenburg Algae.* — E. Lemmermann describes a new endophytic 

 species of Calofhrix, found by him among Nostoc IAnckia, collected in 

 Nieder-Lausitz. He calls it C. marchica and gives a figure of it. 



Problems of a Modern Study of Plankton. | — V. Brehm publishes a 

 sketch of a course of study at the Lunz fresh-water station in X. Austria. 

 He gives first a history of the development of research in fresh-water 

 plankton — Apstein's use of the Hensen methods, and "Wesenberg's work. 

 The author considers that future work in plankton will be characterized 

 by problems of heredity, which are unapproachable from other sides. 

 He describes in detail the views held by authors on the colour and form 

 of various plankton units, and unfolds the latest theories on cyclomor- 

 phosis and cycles of generation. The work should interest botanists as 

 well as zoologists. 



'& j 



Culture of a Plankton Diatom. i — E. J. Allen records his experi- 

 ments on the culture of the plankton diatom Thalassiosira gravida C'leve, 

 in artificial sea-water. He shows that cultures in a purely artificial 

 medium, though prepared according to the most accurate methods, were 

 not successful. But if even less than 1 p.c. of natural sea-water were 

 added to the artificial medium and the whole were sterilized, then the 

 cultures obtained were excellent. These results seem to show that 

 natural sea- water contains some specific substance, without which no 

 vigorous growth of the diatom can take place. The experiments are 

 described in detail. 



Marine Plankton. § — G. Stiasny writes a general accouut of mariue 

 plankton. Plankton and nekton form together the living world of 

 pelagic waters, and plankton stands in close connexion with benthon 

 which inhabits the bottom of the sea. The method of life and the 

 form of plankton alga3 are based on adaptation to conditions of life, 

 which causes greater variety in floating apparatus. In the plant world 

 only few lines of descent can trace their origin to plankton, while in the 



* Abh. Naturw. Ver. Bremen, xxiii. (1914) pp. 247-8. See also Bot. Centralbl., 

 cxxviii. (1915) p. 7. 



t Jahresb. k.k. Staatsgym. in Eger, Bohemia, 1913-14, pp. 1-20. See also Bot. 

 Centralbl., cxxviii. (1915) p. 46. 



I Journ. Mar. Biol. Assoc. United Kingdom, n.s. x. (1914) pp. 417-39. See also 

 Bot. Centralbl., c::xviii. (1915) p. 46. 



§ Schrift. Ver. Verbr. Naturw. Kenntn. Wien, liii. (1913) pp. 431-54. See also 

 Bot. Centralbl., cxxviii. (1915) p. 47. 



