748 



Tliis tabic clcai'ly sliows the iiiliibitory action of Ilie salts and 

 at the same time tlu'ii- iiitluejice upon tlie swelling. It also appears 

 iVüni these data that this influence and the inhibitory action proceed 

 collaterally. There is a slight deviation only with the nitrate in such 

 a sense, that the digesting action is a little more intense tiian with 

 the chlorate, which, however, may result from an experimental 

 error, the methods of estimating the swelling and the digestion being 

 comparatively rough. 



With greater concentrations of the salts the order was modified 

 a little, but there was again the side-by-side progress just alluded 

 to; in these greater concentrations the Ch changes more considerably, 

 which renders it slightly more difficult to note the influence. 



Accordingly the sodium salt e.xperiments yield evidence confirm- 

 atory of the supposition that the action of the pepsin is determined 

 by the condition of the substrata. 



In the above experiments the method used allowed me only to 

 make a rough estimation of the condition of the protein and of the 

 digestion. I, therefore, deemed it necessary to carry out some exper- 

 iments affording an opportunity to estimate them as correctly as 

 possible. It is very difficult to thoroughly study the condition of 

 the protein, the size of the molecules in the solution, the taking 

 up of water etc. The 'preceding tests, however, taught us that the 

 swelling seems to play a principal part, which in fact seemed 

 plausible from the very first. 



This swelling can be determined in several ways; when working 

 with protein-solutions we determine it by noting the viscosity. 

 To work with solutions seemed to be the best method to arrive at 

 accurate determinations. Much more difficult it is to correctly' 

 estimate the action of the pepsin. Here the formol-titration defeats 

 our purpose. 1 have employed a method, used also by Sörensen 

 and consisting in the determination of the amount of nitrogen, which 

 after the pepsin has been active for some time, can no more be 

 precipitated by tannin. 



In determining the viscosity it should be borne in mind that it 

 quickly recedes in solutions containing a pretty large amount of 

 acid, especially in the first few minutes after the addition. It is 

 impossible to obtain a perfectly correct estimation of the initial 

 viscosity in solutions with differing amounts of acid; the maximum 

 for instance will always be found among the lower amounts of 

 acid. 1 found that this decrease in the viscosity is very much 

 quickened by pepsin, to such a degree that in a very few minutes 

 the rise of the viscosity' by acid is no longer noticeable. From this 



