Algae. 445 



Die Flechtengonidien verhalten sich ganz ahnhch wie 

 Stichococcus. Die schnellste Entwicklung findet bei 0,5 — 1 Proc. 

 Pepton und 1—2 Proc. Glukose statt. Die Concentrations- 

 grenze liegt für Glukose bei 20 Proc. und für Rohrzucker bei 

 40 Proc. Auch bei den Gonidien begünstigt Zuckerzusatz die 

 Entwicklung ausserordentlich. Sehr interessant sind die Ver- 

 suche mit zuckerfreier Nährlösung, der sechs verschiedene 

 Stickstoffverbindungen zugefügt wurden. Während bei Sticho- 

 coccus die Stickstoffquelle keine so grosse Rolle spielt, gedeihen 

 die Gonidien am besten bei Peptonernährung. „Diese deutlich 

 hervortretende physiologische Eigenschaft beruht, wie man an- 

 nehmen muss, auf dem Zusammenleben der Alge mit dem 

 Pilze im Flechtenthallus". Trotz des Mangels an Zucker ver- 

 mögen sich die Gonidien relativ gut zu entwickeln. 



Im Gegensatz zu Stichococcus und den Gonidien zieht 

 Scenedesmus schwächere Nährlösungen, die nur 0,125 Proc. 

 und 0,0625 Proc. an Glukose und 0,0625 Proc. und 0,03125 Proc. 

 der Stickstoffqudlle enthalten, vor. In starken Concentrationen 

 mit über 10 Proc. Glukose gedeiht die Alge nicht. Heering. 



Wesenberg-Lund, C, Acomparative study of theLakes 



of Scotland and Denmark. fProceedings of the Royal 



Society of Edinburgh. Vol. XXV. No. 6. 1905. p. 401 



—448. 2 plates.) 



The author of this paper^ an expert on the subject of plankton. 

 was invited by Sir John Murray to assist in the biohigicai, bathy- 

 metrical and physical explorations of Scottish laiies in 1904. He 

 explored the iakes of the Caledonian Canal and a few Low 1 and 

 lakes, especially Loch Leven. He compares the Danish with the 

 Scottish iakes under each of the follow ing headings: General remarks 

 on the natural conditions of the Danish and Scottish Lakes; the 

 organisms, and their relations to the different life-conditions ; the in- 

 fluence of the organic life upon the Lakes themselves and their sur- 

 roundings. He then adds a few words on his visit to the Low! and 

 Lakes, foilowed by some genera! conclusions not connected with aigae^ 

 and a bibliography. In comparing the organisms of the two countries, 

 he calls attention to the great contrast in nearly every particular. The 

 Scottish lakes are marked by an excess of humic acid and a total 

 absence of lime. The Cyanophyceae are not abundant, nor are certain 

 of the diatoms; whereas the Desmidieae exhibit an astonishing richness 

 and diversity, as has been already pointed out by Messrs. West. 

 The quantity of plankton in the Highland lakes is very poor rela- 

 tively; and the seasonal variations are never so pronounced in the 

 Scottish as in the Danish lakes, probably owing to the more even 

 temperature of Scottish waters. As regards the abundance of 

 Desmids, the author puts forwaid a plausible theory in explanation. 

 He surmises that the Desmid flora in the lakes is constantly being 

 renewed from the surrounding moss-covered hill-sides and the bogs, 

 which form their natural habitat. Incidentally he alludes to the adaptation 

 which is taking place in many of the forms, to fit them for a pelagic 

 life^ such as an elongation of the spines, etc. The colour of Scotch 

 loclis is not affected by the organisms in the manner seen in Den- 

 mark: and the deposition of organic matter is not nearly so abundant. 

 The Scotch lochs are deeper and of a more permanent character 

 than the lakes of Denmark. E. S. Gepp-Barton. 



