60 LECTURES ON IMMUNITY 



these cases a compound of the enzyme and the substrate 

 upon which it acts. If the enzyme is in excess (in the 

 said cases), nearly the whole quantity of the substrate 

 acted upon enters into the compound, the quantity of which 

 is therefore proportional to the quantity of this substrate. 

 If, on the other hand, the substrate is in excess, the quan- 

 tity of compound is nearly proportional to the quantity of 

 enzyme. We may therefore from these experiments draw 

 conclusions as to the quantities of enzyme that are equiva- 

 lent to a certain quantity of, e.g., sugar or milk sugar. 

 These conclusions indicate that the equivalent weights of 

 the enzymes are not so high as is often assumed. The 

 circumstance that enzymes are not in general pure sub- 

 stances hinders the estimation of their true equivalent 

 weights. 



The formula of Bodenstein and Henri may be deduced 

 in the following manner. The quantity 1 of ferment from 

 the beginning may be called F, that of the decomposing 

 substance A. Of this a part, x, may be decomposed so 

 that only A x remains. The ferment, substance A, and 

 reaction-products may enter into compounds consisting of 

 i molecule of ferment with/* molecules of A and q mole- 

 cules of different reaction-products. Of these compounds 

 z, z lt etc., molecules may be present. Then for every one 

 of these kinds of molecules a formula of the following 

 form is valid : 

 2 = k l F l (A-x- 2/*) (x - 2?*) where F= F 1 + 2*. 



If we suppose ^.z to be small as compared with A and 

 x, we get z = kF l (A - 



1 Cf. Henri : Compt, rwd< 135. 916. 



