330 ORGANISATION IN SPACE AND TIME 



by one, but by several pathways, just as the quickest way of 

 getting from one place to another over a railway system with 

 many branches and loops may involve the use of different 

 routes comprising combinations of different sections of rail- 

 way line. In chemical kinetics, when alternative routes of 

 this sort are available, special importance naturally attaches 

 to the route along which the reaction can proceed at the 

 greatest speed under the given conditions. But we must 

 not forget that (as all motorists know) the shortest way is not 

 always the fastest, and it is often better to follow a circuitous 

 route which runs over a well-made highway. Similarly in a 

 complicated network of chemical reactions it often happens 

 that a process of transformation comprising a large number 

 of separate links is carried out very quickly to achieve a 

 chemical transformation which is based on but one, or a few, 

 chemical acts. 



Thus, in a complicated network of chemical reactions the 

 attainment of the highest speed for a process involves not 

 merely the speeding up of one of its stages, but the establish- 

 ment of the most effective relationship between all the para- 

 meters of the process. In addition, any alteration in the 

 external conditions acting on the process, by speeding up 

 or slowing down any one stage of the chemical transforma- 

 tion, will lead to a rearrangement of the kinetic parameters 

 of the system as a whole. 



The establishment of such a network connecting the 

 kinetic parameters under the influence of a change in the 

 external conditions does not, according to A. C. R. Dean and 

 C. N. Hinshelwood," take place instantaneously but requires 

 a certain time for reconstruction. In its establishment the 

 attainment of the best rate for the process is sometimes even 

 hindered for a period to allow the working of less effective 

 alternative processes which, however, are already in action. 



All these processes can not only be worked out theoretically, 

 but can also be demonstrated experimentally, especially by 

 analogy with a hydrostatic model in which there are 

 several stationary systems having common original and final 

 reservoirs. 



We may summarise all that has been said about the 

 thermodynamics and kinetics of open systems by stating the 



