ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 559 



that of the north-west and south- west of Iceland. Characteristic of the 

 Faeroe algal vegetation is the specially rich development of the littoral 

 region. He is able to endorse the views held by Kjellman on the 

 systematic relations of Acrasiphonia. The Desmid flora is nearly related 

 to that of western Europe, especially the British Isles, bnt it possesses also 

 a distinctly Arctic element. The book is illustrated by good photographs 

 of alga? in situ. It is written in Danish. 



Plankton of the Danish Lakes.* — C. Wesenberg-Lund embodies in 

 this paper the results of the biological studies in fresh-water organisms 

 carried out in the Danish Laboratory since 1897. The paper begins 

 with an introduction dealing with former work on the subject, and 

 explains the lines of the author's own investigations. In the first 

 chapter there is given a topographical account of the lakes, height above 

 sea-level, streams falling into or running out of them, etc. In the 

 second chapter the author describes his methods of investigation, and 

 in the third he deals with the general formation, the physical conditions, 

 and the temperature of the lakes. The fourth and following chapters 

 contain remarks on the Cyanophycese, Diatomaceas, Chlorophycea?, and 

 Zooplankton of the region. The numerous illustrations are reproduced 

 from photomicrographs. Explanatory tables give the date of capture, 

 and frequency or rarity of occurrence. 



Analysis of the Colour of Algse.f — N". Gaidukov has examined the 

 light absorption of certain living alga? with the help of Engelmann's 

 microphotometer. The species chosen were the green Gladophora fracta 

 Kutz., the blue-green OsciUaria aermjineo-ccurula Kutz., a red Ceramium 

 species, the yellow-brown Dictyota clichotoma Lam., brown Funis serra- 

 tus, and violet Chondrus crispus. A permanent mount of Gryptoglena 

 ccerulescens Ehrb., with blue chromatophores, was also analysed. The 

 spectroscopic results which are given showed a remarkable likeness, only 

 the spectrum of the green cells differing somewhat more markedly from 

 the others. Colours formed artificially in the algae by treatment with 

 acids and alkalis show much the same spectra as the natural colours. 



Growth of Algse in Water Supplies.} — G. T. Moore and K. F. 

 Kellerman have made a special study of the algae found in many reservoirs 

 of drinking water, and have experimented in methods of exterminating 

 them, in order to render the water once more fit for use. They find 

 that the disagreeable odour and taste often present in drinking water 

 are due almost exclusively to alga?, and the methods employed for re- 

 moving this trouble are expensive, or in some way unsatisfactory. They 

 therefore recommend the use of copper sulphate in a dilution so great as 

 to be colourless, tasteless or harmless to man, while it is sufficiently 

 toxic to the alga? as to destroy or to prevent their appearance. The cost 

 of this treatment is slight, and the result very satisfactory. Details are 

 given in tabulated form of the result on certain species of alga?, as well 

 as on pathogenic bacteria. 



* Dansk. Ferskvands-Biolog. Labor., v. (1904) pp. 223 (S maps, 10 pis.). 



t Ber. Deutsch. Bot. Gesell., 1904, pp. 23-9 (1 pi.). 



X U.S. Department of Agriculture, Bureau Plant Industry, 1904, 44 pp. 



