DURING the past ten years in which the investigation of micro-organisms and their functions has been so actively pursued there has been a conspicuous absence of any work dealing with the progress made in our knowledge of those particular forms which are of industrial importance. Thus whilst numerous text-books in various languages have appeared embodying the latest discoveries in the relationship of micro-organisms to disease, the only noteworthy treatise on the technological side of bacteriology since Pasteur's “Etudes sur le Vin, le Vinaigre, Ct Ia Biere,” the last of which was published in 1876, is Alfred Jorgensen's “Micro-organismen der Gahrungsindustrie ”(1886), of which the volume before us is an edited translation. This lack of text-books is doubtless in great measure due to the industrial aspects of micro-organisms having been comparatively neglected during the time that Pasteur, Koch, and their numerous disciples have been busily engaged in the investigation of questions of still more absorbing human interest. But whilst the great majority of bacteriologists have during this past decade been thus occupied in establishing or endeavouring to establish the connection between numerous diseases and specific organisms, a few more silent workers have been patiently engaged upon the less sensational though no less arduous task of placing the fermentation industries on a more scientific basis, adding in fact to the structure which had been commenced by Pasteur in his “Etudes”referred to above. The foremost in this field of research has unquestionably been Christian Hansen of the now world-famed Carlsberg Laboratory near Copenhagen, and to a concise and most lucid description of whose successful labours the present volume is chiefly devoted. The principal addition which has been made to our knowledge of the fermentation organisms by Hansen has been the precise characterization of a number of different “races”of yeast and the determination of the specific features of the fermentation induced by each particular race. Thus whilst Pasteur attributed the various diseases in wine and beer to the presence of organisms other than yeast, Hansen has shown that certain races of yeast itself are capable of bringing about most serious disturbances in the fermentation process. The lines on which Hansen has differentiated these several races of yeast, and the methods by which their pure culture may be effected are clearly though briefly described in this work, with which latest developments of brewing technology, both the author and translator have already identified themselves in the past. The Micro-organisms of Fermentation, practically considered. Alfred Jorgensen. Edited from the German by G. Harris Morris, Ph.D., F.C.S., F.I.C., &c. With an Introduction by Horace T. Brown, F.C.S., F.I.C. (London: F. W. Lyon, 1889.)