144 MASS. EXPERIMENT STATION BULLETIN 167. 



1. Choice of methods to measure — 



(a) the hydrogen ion concentration in the culture medium. 

 (6) the proteolytic activity quantitatively. 



2. Choice of a proper medium, i.e., one which gives uniform results 

 biologically, chemicallj'' and physically. 



Diagrammatical Representation 



OF THE 



Problems 



JT, ide ■ 



Present investigation. 



\l\8.T\p. 



3. Preparation of media of different hydrogen ion concentrations so 

 that minimum, optimum and maximum hydrogen ion concentration may 

 be determined. 



4. Acclimatization to secure organism of constant habit. 



5. Inoculation of medium for uniformity of growth. 



6. Test for vitality of the organism in media of different hydrogen ion 

 concentration. 



7. Determination of the rate of growth. 



8. Determination, from time to time, of hydrogen ion concentration. 



9. Determination of the rate of proteolysis. 



10. Determination of the kind of proteolysis, viz., peptic, ereptic, 

 tryptic-like. 



11. Determination of the character of the enzyme, namely, endo- or 

 exo-enzyme. 



