800 
the time to obviate any noxious influence of the flask-wall or of the 
carbon-dioxide upon the reaction, we should detect unmistakable 
influence of the diet, this might be owing to various causative fac- 
tors. First of all the concentration of the enzyme might have been 
altered by the diet. In the second place the organism might effi- 
ciently alter the concentrations of the ions, which are so material 
to the action of the enzyme, especially the H- and OH-ions, as well 
as the Cl-ions and others. 
We thought proper, therefore, to cautiously watch the influence 
of the H- and OH-ions in order to ascertain by subsequent experi- 
ments, whether variations in the activity of the enzvme are to be 
attributed to changes in the concentrations of the said ions. Moreo- 
ver, an accurate knowledge of the influence or these ions may lead 
to a clearer insight into the action of the enzyme. 
Previous inquiries into the effect of acids and alkalis on the action 
of ptyalin yielded rather contradictory results *), from which it was 
supposed that either acids or alkalis acted favourably. 
As a rule we used in our investigations the methods employed 
by SORENSEN?) in his remarkable experiments on enzymic actions. 
We adopted the following course : 
filtered saliva, designated “enzyme” in the following tables, was 
made to act at 87° upon 1°/, amylum solutions. After the action of 
the enzyme had been arrested by heating it was estimated by the deter- 
mination of the reducing power of the digestion-fluid, of the rotatory 
power and by reaction with iodine. Various reactions were given 
to amylum solutions. To obtain them and to maintain them constant 
three buffing- or regulating-mixtures were applied, viz. 
1. phosphate-mixtures, 
2. citrate-mixtures, 
Oo. acetate-mixtures. 
The process of digesting lasted 20 minutes for all series of expe- 
riments but one. 
1. Leperiments with phosphate mixtures. 
(all the glass vessels had been exposed to steam for 15 ininutes.) 
Into ERLENMRIJER-flasks (Jena-glass), capable of holding 300 c.c. were 
placed : . 
10 ee. of a phosphoric acid solution 1.485 n., varying amounts 
of sodium hydrate 0,5670 n., and water up to 50 ce. To this 200 
1) Cf. Hammarsten’s Lehrbuch der physiologischen Chemie. 
2) Comptes rendus des travaux du Laboratoire de Carlsberg. 8me Vol. Ir. Li- 
vraison 1909. 
