384 PROCEEDINGS OF THE OHIO ACADEMY OF SCIENCE. 



more attention is being given to the study of the mechanism of 

 the reactions employed and to the transformations of energy ac- 

 companying these reactions. The chemist is not satisfied in 

 simply knowing, for example, that sugar decomposes into alco- 

 hol and carbon dioxide. He wishes to follow the course of the 

 reaction and to learn the answers to such questions as whether 

 the reaction takes place in steps and if so what conditions bring 

 about each of these changes, what is the mechanism of the 

 changes and what transformations of energy attend them. In 

 the study of these questions much assistance has been rendered 

 by the principle known as the Phase Rule which was advanced 

 by one of our countrymen, J. Willard Gibbs. 



In connection with this line of investigation, mention may be 

 made of the development of the respiration calorimeter which 

 has made it possible to follow with precision all the energy 

 changes involved in metabolism. In this way it has been shown 

 that the changes in matter and energy which take place in the 

 human body are in accord with the laws of the conservation of 

 mass and of energy. 



Fermentation. The work of Buchner upon fermentation 

 has given us some insight into this highly intricate process. 

 At the time of the discovery (1897) Buchner, now Professor of 

 Chemistry at the University of Wurzburg, was engaged in study- 

 ing the effects of yeast extract upon animals. In order to secure 

 this extract Buchner first disrupted the cell walls by grinding 

 the yeast with fine sand an then subjected the resulting mass to 

 a high pressure. In this way he obtained the yeast extract en- 

 tirely free from the cells of the living organism.' In order to 

 prevent putrefaction Buchner used sugar as a preservative. The 

 resulting liquid on standing was found to evolve a gas. Investi- 

 gation soon showed that this was the result of the change of 

 sugar into alcohol and carbon dioxide. By a lucky incident, 

 therefore, Buchner had succeeded in accomplishing what so many 

 others had attempted and failed, namely, the fermentation of 

 sugar in the absence of living cells. In the light of these results 

 the role that the yeast plant plays in the process of. fermentation 

 lies in the secretion of an enzyme (to which the name zymase has 



