344 The American Naturalist. [April, 
established a laboratory for the purpose of giving specialists an oppor- 
tunity of becoming acquainted with the new system, and, at the same 
time, supplying cultures to breweries. While Hansen worked mainly 
in the line of bottom fermentation, Joergensen worked with top fer- 
mentations. 
All we who have had an opportunity of working with Joergensen, 
are well acquainted with his text-book ; it is as thorough as its author 
and as familiar to us as our catechism. 
Chapter I treats of microscopical and physiological examinations in 
the line of lower cryptogams; Ch. II of examinations of air and water, 
including Hansen’s zymotechnical analysis of air and water ;in Ch. III 
bacteria form the subject; Ch. IV contains the moulds, Ch. V (pp. 111- 
203) contains a full account of the alcoholic ferments, methods of 
analysis in this special line, and descriptions of the different species of 
Saccharomyces and their nearest relatives. In Ch. VI the application 
of the results of scientific research in practice (pp. 204-227) is set 
forth, and a bibliography and an index have finally been added. 
Botanists are, asa general rule, too much absorbed by the questions of 
nomenclature, etc., to look into practical questions; therefore, we often 
see, in text-books, very singular remarks on the subject of fermenta- 
tions. A book like Joergensen’s text-book should not be absent from any 
laboratory, chemical or botanical, because fermentations are subjects 
of study in both places, and because the work in these lines is very 
instructive, both to botanists and to chemists. To the special attention 
of all of oe the book of Joergensen is most cheerfully recom- 
mended. 
J. CHRISTIAN Bay. 
