252 X0TICC8 OF BOOKS. 



endospores of beer-yeast. These reproductive bodies, by the bye, must 

 have been long known, since they are figured in so wido-spread a 

 •work as Hogg's " History of the Microscope," thouy;h, no doubt, their 

 bearing on the genetic relation existing between Saccharomycet and 

 other Fungi was not seen : we must add that the author does not 

 make any mention of this relation, an omission which, in our opinion, 

 is decidedly to be regretted. We find, ne.vt, chapters on the chemical 

 composition of ferments ; on the functions of yeast, the main result 

 from the study of which is that yeast possesses tlie power of resolving 

 the sugar which penetrates by endosmose into the interior of the cell 

 into alcohol, carbonic acid, glycerine, succinic acid, and oxygen ; and on 

 a specially interesting and recent study, viz., the behaviour of yeast 

 when left to itself, under which circumstances yeast- cells show a 

 tendency to feed on their own tissues, this being evinced by a weak 

 development of carbonic acid, while simultaneously, by a process 

 similar to that which takes place in the animal tissues, certain of the 

 insoluble, albuminoid substances of the yeast are broken up, with for- 

 mation of acetic acid, leucine, tyrosine, sarcine, &c. In this way we 

 arrive at the conclusion of a very full and careful examination of all 

 the phenomena which occur during the process of alcoholic fer- 

 mentation. 



There are, however, other systems of fermentation, if the expression 

 may be allowed, e.g., the transference of sugar into a viscous mass, in 

 presence of a minute, necklace-forming, globular ferment ; again, 

 certain sugars can be transformed into an acid syrup (lactic fermenta- 

 tion) ; again, it has long been known that urea becomes broken up 

 into carbonic acid and amnionic carbonate, and the author accepts a 

 recently promulgated theory, that this change is induced only in pre- 

 sence of a Torulaceons growth. On each of these subjects we have a 

 chapter, and the series is brought to an end by one on butyric or 

 oily fermentation of sugar, which Pasteur holds to be a result brought 

 about by a species of the genus Vibrio. 



It has been discovered by Pasteur that all these fermenting pro- 

 cesses can go without access of atmospheric oxygen, a fact the signi- 

 ficance of which its discoverer appears to be inclined to push too far, 

 asserting that the influence of oxygen as anutritive factor is eliminated. 

 But whatever view bo adopted as to the function of oxygen in these 

 cases, a well-marked line of demarcation separates them from the process 

 termed acetic fermentation, which is a case of simple oxidation, 

 performed through the mediation of a living organism, the Jfi/codcrma 

 aceti. The chapter on this fermentation by oxidation is followed by 

 others purely chemical, and the work is brought to a close by a review 

 of the " spontaneous generation" question, in which panspermist ideas 

 are adopted. 



We can strongly recommend the book to any person desiring 

 information on thissubject ; in fact, there is nothing like it in the lan- 

 guage for fullness, grasp of detail, and presentation of recent results ; 

 but while so doing we must direct attention to one or two drawbacks 

 which, it appears to us, detract somewhat from its value. Foremost 

 stands the readiness of the autlior to digress into special hobbies, the 

 information which transpires being valuable, no doubt, but with meagre 

 bearing on the subject in hand ; as examples, we would cite the 

 long account of the quantitative estimation of oxygen, and the 



