1128 



If all the atoms, constituting a molecule, receive this radiation 

 from a similar molecule at the same time in the required phase, 

 the reactivity of the molecule as a whole can be expected to have 

 changed. A small increase of the vibration of the molecule may 

 increase its power to enter inlo combination (this point will be 

 treated further on), a large elevation may (ear it out of a compound 

 with other molecules. 



However, the author wishes not at present to lay much stress 

 on the particulars of his hypothesis. The numerous experimental 

 facts, recorded in these papers, for a great deal only revealed by Ihe 

 aid of this guiding hy|)üthesis and which we have all coordinated 

 by drawing their consequences, will prove its usefulness. 



The radiation, by means of which urease acts on urea, thus ori- 

 ginates from the enzyme molecule and is able to exert its hydroly- 

 sing effect to a certain distance, probably microscopically small. 



When this urease-radiation strikes a urea-molecule, it is absoibed, 

 just as for instance the specific radiation of a Na-atom is especially 

 absorbed by a Na-atom. 



The amount of urea, hydrolysed in a time-unit by an enzyme- 

 molecule would therefore be independent of the urea-concentration, 

 if the other coustiluents of the solution had practically no absorbing 

 power towards this radiation. Only with a very small concentration 

 of urea, the radiation might be expected to be, at least partiall} , so 

 much weakened by spreading before striking a urea-molecule, that 

 it has lost the power of hydrolysing it. Hence for very dilute solu- 

 tions of urea constancy of action of a given quantity of urease 

 should not be expected; in these conditions the amount of action 

 will be found smaller. 



So far the theory is the same as that, put forward by the author 

 previously for the sugar-enzymes. 



A new point of dominating importance, at least in the case of 

 urease, is, that the hydrogen-ions proved to be, besides urea, the 

 only constituent in the solution, which absorbs this radiation. 



It seems not improbable, that the way in which the H-ions were 

 found to interfere with the urease-action will appear to play a part 

 also in enzyme-action generally. 



The mathematical formulation of this theory is very simple and 

 gives at once the following differential equation for the reaction 

 velocity at constant temperature and constant H-ion concentration: 



— dx ■=■ m dt (1) 



X -\- nc 



In this equation x is the concentration of the urea (grams per 



