August 31, 1900.] 



SCIENCE. 



345 



tures. The few species known to Pasteui- have 

 become many and distinct in the hands of mod- 

 ern students. The diseases peculiar to fermen- 

 tated products, attributed by Pasteur to bac- 

 teria, have been found to be frequently due to 

 yeasts which are present as impurities, and the 

 whole method of conducting fermentations in 

 the great breweries has been modified in con- 

 sequence. All these facts are brought out in 

 more or less detail in this work of Jorgensen, 

 who shows on every page of his writing a 

 knowledge of the facts at first hand. 



The whole work is not confined to the fer- 

 mentations produced by yeasts. The growing 

 knowledge of the significance of bacteria in fer- 

 mentations has demanded attention, and the 

 more important species of moulds are not over- 

 looked. The treatment of this side of the sub- 

 ject is much less satisfactory than the study of 

 yeasts. In his discussion of the butyric fer- 

 mentation, the lactic fermentation and other 

 strictly bacteriological phenomena Professor 

 Jorgensen is evidently not so much at home as 

 when he is writing of yeasts. 



The most valuable part of the work is, there- 

 fore, the review of our present knowledge of 

 yeasts. He describes the methods of studying 

 air and water ; the most recent methods of 

 obtaining absolutely pure cultures of yeasts, 

 the methods of cultivating them and experi- 

 menting with them. A considerable part of 

 the work is taken up by a description and by 

 figures of the many species of yeasts which have 

 been differentiated from each other by modern 

 study. Their methods of forming spores, of 

 germinating, of forming films, and, in short, all 

 of the characters of yeasts which are used to- 

 day by the specialists in describing yeasts are 

 carefully and fully discussed. As a morpholog- 

 ical and physiological study of this extremely 

 important group of plants the present work is 

 complete and unequaled. Certainly there is 

 uo work in English that contains such a com- 

 prehensive account of the modern knowledge of 

 yeasts and their relation to fermentation. 



The name of The Macmillan Company on the 

 title page is a sufiicient guarantee of the excel- 

 lence of the press work, as the name of the au- 

 thor is a guarantee for its scientific accuracy. It 

 seems strange, however, that the author, the 



translators and the publishers should have al- 

 lowed such a book to be published without an 

 index. A book of this sort may perhaps be de- 

 signed for consecutive reading, but it will be 

 much more commonly used as a book of refer- 

 ence. As a book of reference its value would 

 be doubled by the presence of a good index. 

 No excuse can be given in these days of many 

 books for omitting such an indispensable part 

 as an index. The lack of the index is in part 

 made up by a magnificent bibliography con- 

 taining references to all the important works 

 bearing directly or indirectly upon the problems 

 of fermentation. This will be to the student 

 perhaps the most useful part of the whole work. 



H. W. C. 



BOOKS EECEIVED. 



Air, Water and Food from a Sanitary Standpoint. El- 

 len H. EicHAEDS and Alpheus G. Woodman. 

 New York, John Wiley & Sons ; London, Chap- 

 man and Hall, Limited. 1900. Pp. iv-f226. 

 S2.00. 



Prehistoric Implements. Wabeen 

 Cincinnati, The Robert Clarke 

 XV + 429. 



Die Chemie in tdglichen Leten. 

 Fourth edition. Hamburg and 

 Voss. 1900. Pp. viii -|- 320. 4 



A Brief Course in General Physics, 

 Applied. Geoege A. Hoadley. 

 American Book Company. 1900. 



K. Mooeehead. 

 Co. 1900. Pp. 



Lassae-Cohn. 



Leipzig, Leopold 



Mark. 



Experimental and 

 New York, The 

 Pp. 463. 51.20. 



SCIENTIFIC JOURNALS AND ARTICLES. 



The Journal of Physical Chemistry, April. ' A 

 Preliminary Investigation of the Conditions 

 which determine the Stability of Irreversible 

 Hydrosols,' by "W. B. Hardy; ' On the Mech- 

 anism of Gelation in Irreversible Systems,' by 

 W. B. Hardy ; 'Isohydric Solutions,' by W. D. 

 Bancroft ; ' Vapor-pressure Relations in Mix- 

 tures of Two Liquids,' by A. E. Taylor; 'In 

 Keply to a Statement made by Dr. R. Cohen in 

 a Paper on the Theory of the Transition Cell of 

 the Third Kind,' by H. T. Barnes. 



May. ' On the Weston Cell as a Transition 

 Cell and as a Standard of Electromotive Force, 

 with a Determination of the Eatio to the Clark 

 Cell,' by H. T. Barnes; 'On the Electrolytic 

 Deposition of Metals from jSTon-Aqueous Solu- 



