140 MASS. EXPERIMENT STATION BULLETIN 167. 



several physiologic processes. Sorensen ^ studied extensively the influence 

 of different hydrogen ion concentrations upon enzymes, and concluded 

 that enzymatic action can be controlled by adjusting the reaction of 

 media. In the medical world the phenomena of "acid intoxication'' in 

 different forms have suggested the importance of the study of "true acid- 

 ity" of blood and urine. Michaelis^ pointed out the clinical importance 

 of the "true reaction" of the blood. Henderson and Palmer' have demon- 

 strated the clinical value of "true reaction" in its relation to the urine. 

 Their results are not specific unless they are to indicate the normal and 

 abnormal condition of the body. 



In agriculture, several perplexing problems have presented themselves 

 in which the hydrogen ion concentration is involved. Such subjects as 

 the acidity of soil, of plants, of milk and of many other substances in 

 both the organic and inorganic world are now the problems of agricultural 

 investigations. Since this acidity is caused only by the dissociated hydro- 

 gen ions, regardless of the exact nature of the chemical compound, a 

 better understanding of the "true reaction" is evidently desirable. 



The importance of proteolysis in decomposition of proteins is so well 

 understood that further consideration is unnecessary, except a mention 

 of its association with dairy, food and soil studies. So much weight is 

 attached to it that it has become fairly basic to all scientific advancement. 

 In order to make the study yield easily to confirmation, B. stibtilis has 

 been selected because of its well-known characteristics for identity. This 

 organism makes a good starting point from which the proteolysis of other 

 organisms may be investigated and paralleled. 



While we recognize that hydrogen ion concentration is only one factor 

 in proteolysis, the significance attached to it must lend considerable force 

 to its solution. The progress has been extremely slow awaiting the devel- 

 opment of the chemistry of proteins. The author is familiar only with 

 Sorensen's formol titration method * as the one serving to secure the addi- 

 tional knowledge of proteolysis. So far as it has been applicable it seems 

 very satisfactory. 



Classification in microbiology seems at present to be based upon the 

 morphology and biometric characters. There is a subcurrent of feeling 

 that physiologic properties are so variable that they are not reUable. 

 This may not hold true, however, if it becomes possible to use more exact 

 physiologic methods, for through them may be found those delicate differ- 

 ences which are more or less constant and recognized in the metabolism 

 of higher organisms. Then, too, if morphology is a mere expression of 

 physiology and the molecular mechanism of organisms, there is greater 

 reason for looking more deeply into the relation of hydrogen ion concen- 

 tration as manifested in different species and varieties. 



1 Ergebnisse d. Physiologie, 12, 449 (1912). 



2 Die Wasserstoffionenkonzentration, 85, 1914. 



» Jour, of Biol. Chem., V. 13, No. 4, Jan., 1013. 



* E. Abderhalden. Handb. d. Biochem. Arbeitmethoden, Bd. 6, S. 262, 1912; Comptes rendus 

 du Laboratoire de Carlsberg, 7, 1, 1907; Biochem. Zeitschr., 7, 43, 1907. 



