510 



Dr. E. F. Armstrong. 



[Apr. 5 ? 



Concentration of Enzyme. — Lastly, Table XVII shows the effect of 

 varying the amount of enzyme present. Experiments in this direction 

 are limited by the uncertain nature of the material, as well as by the 

 fact that it is the concentration of enzyme relatively to that of sugar 

 which must be studied. ' The solution contained 5 per cent, of sugar. 

 Solutions containing varying amounts of enzyme were obtained by 

 diluting portions of one and the same stronger solution. The weight 

 hydrolysed in a given time by varying amounts of enzyme was 

 approximately proportional to the amount of enzyme, provided that 

 the amount was not too large and also that the comparison was 

 made during the earlier stages of hydrolysis before the secondary 

 products began to exert a marked influence. 



Table XVII. — Proportions Hydrolysed in 100 c.c. of a 5 per cent. 



Solution. 



Solution containing 



1 '5 hours. 



20 hours. 



25 hours. 45 hours. 



68 hours. 





0-15 



0- 4 



1- 6 

 3-2 



2 2 

 5 -8 

 23 3 

 45 -8 



2 '6 3 -9 

 6-8 j 10 -2 

 — 38-6 

 54 -5 j — 



4-8 

 12 -6 

 48 -5 



2 '5 c.c. lactase. . . . 



10 „ „ .... 



20 „ „ .... 



Very small quantities of the enzymes lactase and emulsin were 

 found to be capable of hydrolysing only a small amount of sugar : 

 their action then ceased. This result affords very definite evidence in 

 favour of the view that the products of hydrolysis — in this case 

 glucose and galactose — are capable of combining with enzymes and of 

 removing them from the sphere of action. 



Table XVIII. — Proportions Hydrolysed in 100 c.c. of a 5 per cent. 



Solution. 



Solution containing 



24 hours. 



144 hours. 



- 66 c.c. lactase. . . . 



2 -3 



2 3 



1-0 „ „ 



3-2 



3 "5 



2-0 „ „ 



6 3 



7 -4 



5-0 „ „ .... 



15 '4 



34 -0 



Summary and Discussion of Besults — Nature of Enzyme Action. 



From the results recorded in the foregoing tables, it is clear that 

 two periods may be distinguished in the course of change — an earlier 

 period, during which the change is a linear function of the time ; and 

 a later period, during which change proceeds at another rate (Tables 



