CHEMICAL EQUILIBRIA 101 



antigen (see p. 17). The specificity is not absolute 

 as we see in this case, for the antibody reacts both 

 against paranuclein and against casein, notwith- 

 standing that these substances are not identical. 



The first observation in this direction was made by 

 Croft Hill in 1898, who found that maltase from 

 yeast, acting for a month on a 40 per cent solution of 

 glucose, gives a substance similar to maltose, which 

 latter may itself be decomposed by maltase into 

 glucose. This was regarded as a synthesis of 

 maltose due to an equilibrium. But later on it 

 was proved that the substance obtained by Croft 

 Hill was not maltose, but isomaltose, which is 

 itself not decomposed by maltase. In an analogous 

 manner Emil Fischer and E. F. Armstrong syn- 

 thesised, with the aid of lactase from kephir, from 

 galactose and glucose, the hydrolytic products of 

 lactose, not lactose but isolactose, which in contra- 

 distinction to lactose is not attacked by lactase. 

 And Armstrong found that emulsin has the opposite 

 effect to maltase ; it hydrolyzes isomaltose and builds 

 up maltose from glucose. It is therefore clear that 

 here we are not dealing with syntheses of substances 

 in equilibrium with their products of decomposition, 

 as was at first believed. The observed peculiarity 

 is probably due to a binding of the different sub- 

 stances to the enzymes, whereby different equilibria 

 are produced by different enzymes. 



A real equilibrium of a very instructive kind, in 

 which enzymes are acting, has been investigated by 

 Bourquelot and B ridel {Journal de Pharmacie et 



