550 POPULAR SCIENCE MONTHLY. 



would cause the formation in living matter of a great number of 

 s}Titlieses bj tlie building of anhydrides with the formation of water. 

 The cliief difference between living and lifeless protoplasm was about 

 the difference between an anhydride and an acid. When death 

 ensued, oxidation no longer took place, but the saponification con- 

 tinued until complete. 



Although this hypothesis is necessarily difficult of proof, many 

 facts indicate its possible truth. That protoplasm is the seat of 

 reduction and oxidation no one will probably deny, and that by a 

 process of alternate reduction and oxidation many of the transforma- 

 tions of substances by the organism may be repeated outside the cell 

 is also undoubted. Thus Drechsel, by a rapidly alternating electric 

 cuiTent, has succeeded in producing urea from albumin. It is also 

 well recognized that many of the best-known syntheses effected by 

 the organism are formed by a dehydration. This is true of the 

 formation of fat, of the ethereal sulphates, of hippuric acid, of 

 the camphor-giycuronic acid, and of the chondroit-sulphuric acid 

 of cartilage. In this manner, too, as Hoppe-Seyler discovered, 

 fatty acids of many carbon atoms may be synthesized from 

 comparatively simple compounds. It seems not improbable that 

 Hoppe-Seyler thus obtained a glimpse of that promised land 

 toward which the physiological chemist has been patiently work- 

 ing for the past forty years, where the mysteries of protoplasm 

 shall be made clear. Whatever may be the exact details of the 

 process of respiration, certainly Hoppe-Seyler's discovery that 

 reducing substances in the presence of air may induce powerful 

 oxidations is one of the most brilliant and suggestive made in bio- 

 chemistry. 



Impressed by the similarity of living and fermentative processes, 

 Hoppe-Seyler devoted much time to the chemistry of the latter. He 

 made the first classification of fermentations, distinguishing those 

 in which a simple hydration or saponification takes place, as in 

 the digestive fermentations, from those characterized by the trans- 

 ference of an oxygen atom from a hydrogen to a carbon atom, with 

 the liberation of hydrogen. To a certain extent he made clear the 

 chemical processes of fermentation, and his researches serve as a 

 solid and suggestive basis for further work. Hoppe-Seyler was 

 throughout a strenuous upholder of the Liebig view of the essential 

 identity of fermentations, whether induced by chemical bodies or 

 living germs. His position has been justified by the recent brilliant 

 discovery that the alcoholic fermentation of sugar by yeast, long 

 believed to be dependent on the life of the yeast cell, is due to a 

 substance which may be isolated from the living yeast. Hoppe- 

 Seyler contributed also to our knowledge of the fermentation of 



