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to attack, does not entitle us to doubt that the size of the pepsin- 
molecule is as great as previous observations have assigned to it. 
On the other hand it seems to me, that the bearing of protein 
on the movement of pepsin through a gel, favours the hypothesis 
that the combination of an enzyme with the ‘‘zymotele” is not to 
be ascribed only to adsorption, but also to a totally different action 
depending on the structure of the molecules. 
On starting this inquiry I purposed to extend it in various direc- 
tions and over more enzymes, notably invertin and emulsin, which 
can attack various carbonhydrates of known structure. But I under- 
stand that my time for Laboratory work is passed. I must now 
leave this to younger workers who consider this subject interesting 
enough to investigate it further in the indicated direction or in their 
own way. 
