CATALYSIS AND BIOCIIEMIC.\L PROCESSES 225 



adhesion of the enzyme to the substrate is characteristic; 

 and the influence of electrolytes on enzyme-processes 

 is probably in large part to be referred to their influence 

 on adsorption.^ 



In the simple adsorption type of catalysis the acceler- 

 ating effect depends on the concentration attained at the 

 interface. Close adhesion of the reacting compound 

 to the adsorbent surface is important since this implies 

 a high concentration at the surface. Hence a corre- 

 spondence between the molecular configuration of the 

 adsorbing surface and of the adsorbed compound is 

 favorable to adsorption as well as to chemical combina- 

 tion. The importance of such conditions is seen in the 

 growth of crystals, in which, according to ]\Iarc, the 

 dissolved molecules are abstracted from the mother- 

 liquid and deposited on the surface of the crystal by a 

 process identical with adsorption.^ Slow growth is 

 favorable to the formation of large crystals, because 

 time is then allowed for the regular orientation of the 

 surface-molecules thus deposited. Organic growth 

 apparently also depends on the apposition of newly 

 formed molecules to the similarly constituted molecules 

 already laid down in the soHd state as structure; and 

 this consideration may explain why, in living organisms, 

 where definiteness of form and of structural characters 

 is essential, the rate of growth is slow. Probably no 

 essential distinction is to be drawn between adsorption 

 and chemical combination; in adsorption the surface 

 molecules of the adsorbent are alone concerned because 



» Cf. Bayliss, "Adsorption as a Preliminary to Chemical Reaction," 

 Proceedings of the Royal Society, B, LXXXIV (191 1), 81. 



» Marc, op. cit. 



