INTRODUCTION 3 



What must be the ultimate aim of chemical biology is to establish 

 the sequence of events in the cycle from simple to more complex sub- 

 stances and the disintegration of the latter for the purposes of liberat- 

 ing energy and of so acting on other chemical compounds as to make 

 these available to each individual cell. 



An arrangement of compounds on such a physiological basis is as 

 yet beyond us, for although we know a certain amount about the 

 normal disintegration of albumins into amino-acids, we know nothing 

 as to the physiological processes by which amino-acids are built up 

 into albumins. That the nuclear compounds are the active agents in 



>.v- 



A. Cell : , cytoplasm ; b, nucleus ; c, chromatin ^segment ; d, ionising enzymes ; e, food entering 



nucleus ; /, food being stored by de-ionising enzymes. 



B. Food which is being digested or ionised. 



this building up of higher compounds the author knows from his 

 histological research, and he is at present engaged in adducing chemical 

 proof, apart from experiments on plants and animals. 



In the following chapters a purely chemical classification has been 

 adopted by the author ; the individual substances being arranged in 

 such a way as to lead from the lower members of a series to the higher 

 ones, from the less to the more highly oxidised forms, and from open 

 chain- to ring-compounds. 



Due stress has also been laid in the eighth chapter on the imports 

 ance of salts in converting dead pseudo-amino-compounds into living 

 ones. 



Proteids are met with in nature in one of the following states : 



1. In the form of solution in the fluids of animals or plants, as, 

 for example, in blood, lymph, and cell sap. 



