SECTION I.— PHYSIOLOGY. 



THE SYNTHETIC ACTIVITIES OF THE 



CELL. 



ADDRESS BY 



PROF. H. S. RAPER, C.B.E., F.R.S., 



PRESIDENT OF THE SECTION. 



It has long been the custom to divide the chemical transformations which 

 occur in living animals into anabolic and catabolic. The anabolic are 

 associated with those processes of restitution which occur after functional 

 activity and the catabolic with those accompanying the functional activity 

 itself. This distinction must not be taken to imply that they are inde- 

 pendent. In certain instances we know that the reverse is true. Hence 

 the synthesis of one substance may require the concurrent degradation of 

 another. 



A review of present-day knowledge of chemical processes in the cell 

 reveals the undoubted fact that physiologists have been more successful 

 in investigating the phenomena of catabolism and chemical degradation 

 in the cell than the processes of synthesis, although during life they may 

 and do occur together. This might be expected. Catabolic processes may 

 persist long after the cell has ceased to possess those fundamental proper- 

 ties which we associate with life. They may be demonstrated in cells 

 which have been submitted to mechanical injury so as to destroy their 

 structure or after various methods of treatment have been applied to 

 extract the cell contents. Their investigation has thus proved relatively 

 simple because restrictions as to experimental method have not been severe. 

 But the anabolic processes of the cell are essentially those which occur only 

 during life. To study them successfully demands that the cells in which 

 they are taking place must be kept alive during the investigation. This 

 in itself implies that the range within which the factors determining their 

 progress or cessation can operate is probably as restricted as the conditions 

 determining the life of the cell itself. It is not surprising then that with 

 such severe limitations we have learned up to the present a great deal more 

 about degradation than synthesis in the cell. Nevertheless, the synthetic 

 activities of the cell have a fascination which in itself makes an attempt 

 to discuss them attractive. And I must confess that it was partly for that 

 reason that I chose the subject of this address. It was also my good 

 fortune before proceeding to the study of physiology to pass through a 

 school of chemistry and this may explain in part my predilection for the 

 synthetic processes of living organisms. The chemist, if I am not mis- 

 taken, is more proud of his achievements in the synthetic field than in the 



