No. 606] 



BIOLOGICAL ENIGMAS 



molecules of the solute. In this way the crystal or poly- 

 meric molecule will be built up out of two components by 

 the simultaneous and parallel action of two initially com- 

 bined species of molecular tields. Tlii> chaimv cat- 

 alyzed by the crystal, and is an autocjita lytic ]>r()(T>- in- 

 volving the s}Tithesis of two substances. It is clear that 

 any number of substances may be influenced in this way 

 by a similar, but more complex initial crystal form. 



However, our explanation still remains somewhat spe- 

 cial in its application, as in the majority of cases the 

 products of catalysis do not adhere permanently to the 

 catalytic surface. The extension of the explanation to 

 cases of this sort is not difficult, since we have already 

 seen that, even in the case of crystallization, the heat 

 vibrations of the atoms are constantly tlirowing off molec- 

 ular groups from the surface of the solid. As pointed 

 out by Langmuir, the attraction between the surface and 

 two molecular groups which have a strong affinity for 

 each other may be less than the sum of the attractions of 

 the surface for each of the groups, when separate.-'' This 

 is due to the "ch>sinii- up" or contraction of the iields of 

 force of tlic - loiip- a< ilicy come together. Hence com- 

 bined groui>s ()!" \\[\> >i)v\ will l)e more easily detached 

 from the sui-lace tliaii will the uncombined groups, which 

 will tend to be held in ])la('e until their mates fall into the 

 right positions. The catalytic surface thus acts like an 

 orienting sieve which on account of its s])ecial structure 

 forces a chaotic crowd of individuals which come into con- 

 tact with it, to fall into a special configuration. ^lany 

 machines which accomplish exactly this effect are in use 

 in the industries. 



Thus far we have dealt only with the mechanism of 

 autocatalysis. Heterocatalysis is probably to be regarded 

 as an extension of the process of autocatalysis. It is 

 oln-ious that exact similarity of the force patterns of the 



(Ifc^l, i; catal.Mh- ctVccl A\';ich i^ ha^.-l iip,*!! <iitvct Mini- 



