THE sanitary examination of water supplies by bacteriological methods is becoming of increasing importance. In this country extensive researches have been, and are being, carried out for the Local Government Board, for the Sewage Commission, and for the Metropolitan Water Board. In America also much attention and research are being devoted to the bacteriological examination of waters, and the book under review gives a good summary of American views, procedure, and technique relating to this subject. On the whole, British and American procedures are very similar, and the characters which are recognised by both as belonging to the typical Bacillus coli, so important a factor in all examinations, agree fairly closely. This is important, as it renders results obtained in both countries more comparable than otherwise might be the case. Elements of Water Bacteriology, with Special Reference to Sanitary Water Analysis. By Prof. S. C. Prescott Prof. C. E. A. Winslow. Pp. xii + 258. Second edition, re-written. (New York: John Wiley and Sons; London: Chapman and Hall, Ltd., 1908.) Price 6s. 6d. net.