CHEMISTRY 235 



which occur within the organism are the only 

 ones of this class. There is no more common 

 and universally important reaction in organic 

 chemistry, and many compounds and classes 

 of compounds which have nothing to do with 

 the organism undergo hydrolysis. Moreover, 

 generally speaking, all reactions of this class 

 are very similar in their principal character- 

 istics, resembling one another both dynami- 

 cally and statically. Spontaneously they oc- 

 cur not at all, or very slowly. Under the 

 influence of enzymes, of acids, and of alkalies 

 acting catalytically, that is to say, facilitating 

 the process without in the end taking part 

 in it, much as oil facilitates the action of a 

 machine, they progress rather slowly and 

 very smoothly. By-products are not formed ; 

 the reactions are simple, uncomplicated, and 

 reliable. Hence they enable the organism to 

 make all sorts of rearrangements and recon- 

 structions of chemical substances efficiently 

 and without loss of material. 



The chief cause of such traits in hydrolysis 

 is the fact that the energy transformation 

 which accompanies the process is almost 

 exactly nil. For it has been found in general 

 that chemical reactions which liberate much 

 energy are violent, hard to regulate, often 

 complicated by intricate side reactions, and 



