Surface Tension and Ferment Action. 



583 



instance, the formation of chloroform from chloral by alkali, is a well known 

 fact. In the present case it has been found that the action of invertase on 

 cane sugar may be retarded even although the effect of adsorption is not 

 noticeable under the conditions of the experiment. It has also been found that 

 in some cases the retardation disappears almost completely when the influence 

 of surface tension is removed after it has been operative. Observations such 

 as these would be most readily explained by assuming that the second phase 

 of ferment action .has been inhibited by surface tension and not the first phase. 

 But even when there is no evidence of adsorption we cannot exclude the 

 possibility of surface concentration occurring without adsorption. In other 

 words it seems possible that the ferment goes into the surface layer of the 

 liquid without becoming adherent to the solid and without being removed 

 with latter. Such a condition would also explain the observations referred 

 to above. 



We have convinced ourselves by a number of preliminary experiments that 

 the retardation by surface tension is a phenomenon shown by other ferments 

 besides invertase. The conditions in the case of other ferments have not been 

 studied by us in detail. But it is evident that the effect obtained may differ 

 with the nature of the ferment, of the substrate, of the products of ferment 

 action, and of the surface. If for instance the substrate itself is surface active-, 

 the conditions will differ markedly from those which obtain when the 

 substrate is surface inactive. 



