Fermentation. By P. Sohiitzenberger. (Henry S. King and Co.)— The
study of fermentation has a twofold interest, chemical and biolo- gical, and is intimately connected with a theory which has had eminent adherents and opponents, that of spontaneous generation. This volume, therefore, forms a valuable addition to the "International Scientific Series," inasmuch as we.know of no other monograph existing in Eng- lish on this subject, and it has been treated in a most exhaustive manner by the learned professor, who incorporates in the work many of his own observations. In the first book the author treats of direct fermentation, which is due to cellular organisms of the genus saccharomyces ; in the second, of soluble or indirect ferments, which play such an important part in the animal economy. By an ingenious method invented by M. Schiitzenberger of accurately measuring the amount of oxygen con- tained in a liquid, the respiration of yeast has been fully demonstrated, which would seem to support M. Pasteur's theory that the plant takes the oxygen out of the glucose for its own existence, reducing it to alcohol, were it not equally clearly demonstrated that nutrition and respiration increase side by side, and the reduction of one necessitates the reduction of the other. Another remarkable property in yeast is that it contains the necessary substance for changing saccharose into glucose, upon which alone the organism can act. The final chapter is devoted to spontaneous generation, which has been more fully treated by Mr. Noel Hartley in his late work on the air.