326 Prof. Armstrong, Dr. Armstrong, and Mr. Horton. [Apr. 2, 
fable i. 
5 grammes milk-sugar per 100 c.c. X = percentage amount hydrolysed. 
| 10 c.c. enzyme. | 20 c.c, enzyme. 
Time. 
x K. | x. | K. 
hours. 
2 4 *4 0 00975 8 °3 0 0018 
3 6°8 0 -0102 12 ‘1 0 0184 
5 13 ‘2 00113 21 °*4: 0 0209 
7 18 ‘O 0 °0123 31°9 0 *0238 
10 20°8 00101 42 °3 0 -0239 
24, 40 °5 0 0094: 61:0 0 -0170 
27 42 °5 0 -0089 64°5 0 0166 
75 70 ‘3 0 :0070 83 °3 0 °0104: 
40 ¢.c. enzyme. 60 c.c. enzyme. 
Time. The 
x K. X K 
hours. 
2 15 ‘2 0 '0358 18 °5 0 044.4: 
3 18 °5 0 0296 22 °7 0 0373 
5 21 ‘1 0 ‘0251 36 °5 0 ‘0394 
7 33 °5 0 °0253 4.4. °9 0 0380 
9 42 °2 0 0264: 52 °5 0 0360 
10 44, °O O °0252 53 °5 0 :0332 
24; 73 *4 0 ‘0240 76 0 0 0258 
part of the table, in which are recorded the results of experiments made with 
four and six times the amount of enzyme used in the experiment just 
described. It will be noticed that when the fourfold amount was used, the 
quantity of enzyme was such that the hydrolyst no longer had unlimited 
choice, but was forced to compete for the sugar molecules: being dependent 
on the proportion of unhydrolysed molecules, the rate of change followed the 
simple mass-action law, as shown by the approximately constant value of K 
after about three hours. 
Using the fourfold and sixfold amount of enzyme, the rate of change is 
such that the influence of the products of change soon becomes of con- 
sequence ; a decreasing series of values is therefore obtained. On comparing 
the values found, it is obvious that at first, when the amount of enzyme used 
was doubled, the rate of change was doubled ; subsequent additions, however, 
did not produce the proportionate increase in the rate of change.* 
* The experiments were all carried out at 38° in precisely the manner already explained 
(No. II). Jena-glass vessels were used throughout, with the exception of the pipettes. 
The data given are quoted as illustrations of the results obtained in a number of similar 
experiments. 
