VELOCITY OF REACTION. HOMOGENEOUS SYSTEMS 83 



probable that the rule for this calculation agrees well with 

 the facts only for short times ; a closer examination of this 

 circumstance can be done only when we know the limit 

 values of the change of conductivity, and even then new 

 observations ought to be carried out and multiplied. 



The above calculation is carried through on the assump- 

 tion that the products of digestion from casein exert the 

 same binding influence on the reacting bodies (probably 

 the trypsin) as do the corresponding derivatives from gela- 

 tin, since they cause the same change of the conductivity. 

 This, of course, need not necessarily be the case; it is 

 only the simplest hypothesis we may introduce in the 

 present undeveloped state of research on this point. 

 Hence it is not necessary at all to suppose that the trypsin 

 is bound by the gelatin and the casein to explain that the 

 observed effect on digesting gelatin and casein simultane- 

 ously is less than the sum of the effects of the digestion 

 of the two substances separately, as Henri and Larguier 

 suppose. Their hypothesis might be well founded, if we 

 could observe the digestion in such an early period where 

 the quantity digested was proportional to time, or, in 

 other words, when the products of digestion would be 

 much inferior in quantity (according to equivalents) to 

 the quantity of trypsin. But this condition is not ful- 

 filled in these or in any other experiments on tryptic 

 digestion. 



With the use of a different substratum, however, the 

 action of trypsin exhibits a different behaviour. As deter- 

 mined by Taylor, 1 when protamin is digested by trypsin, 

 the acceleration produced by the ferment is directly pro- 



1 Taylor, University of California Publications, Pathology, I, 21, 1904. 



