271 
In this connection we are induced to suppose that the particles 
of the enzyme are continually moving, while incessantly particles 
of the substrate are being decomposed. So, when a certain amount 
of pepsin is going to spread into the protein-containing gel through 
diffusion, the particles of the pepsin will first be bound to the 
protein-molecules by adsorption, through the difference in the charge. 
If only adsorption should come into play, a large number of the 
pepsin-molecules would be detained, without undergoing or causing 
any change, while the subsequent diffusion would be inhibited rather 
than accelerated. It makes a great difference, however, if in virtue 
of their constitution the molecules of the enzyme also grasp the 
protein-molecules and they attach themselves to new intact protein- 
molecules with which they come into contact, after the splitting of 
the protein and, consequently, because free protein-particles are 
lying on the periphery, they move towards the periphery, and 
— seemingly — quicken the diffusion. 
Now in the experiments which gave rise to BriJerinck’s objection 
the agar-gel contained protein. The question, therefore, was, whether 
in such a gel, ceteris paribus, the spreading of the pepsin would be 
quicker in the presence of protein than in a gel without protein, 
in which only true diffusion would take place. 
— To my friend and successor Prof. W. EK. Rincer | feel greatly 
indebted for his highly appreciated help in my endeavours to find 
an answer to this question in his laboratory. The inquiry was cor- 
ducted as follows: 
25 mers of purified pepsin from the pig’s gastric mucous membrane 
was put in a test-tube, dissolved at body-temperature in 2,5 cc. 
0,2°/, HCI, and subsequently 2,5 cc. 3°/, agar-agar in water was 
added. By rapid shaking the pepsin was evenly mixed up with the 
heated agar-agar and immediately after cooled down in melting ice. 
The small clots of coagulated agar sticking to the wall of the tube 
consequent on the shaking, were whisked cautiously away and, in 
order to destroy all the pepsin that might be left behind in the tube 
above the coagulated column, the tube was filled with 1°/, NaHO, 
then emptied after some moments and washed out a couple of times 
with water and afterwards with 0,1°|, HCl. After this 10 cc. of a 
mixture of 5 ce. agar-agar 3°/, and 5 ce. 0,2°/, of HCl to which 
protein was added or was not, was put into the tube. Then the 
tube was cooled down again in ice. In each experiment four tubes 
were filled in this way, two with and two without protein. They 
were then closed with a cork stopper, placed vertically in an in- 
cubator that was kept at 27° C. 
18* 
