recent work on bacterial variants, in chiding the much discussed 

 " Twort d'Herelle phenomenon " of transmissible bacterial 

 autolysis. He points out that all these different manifestations 

 of bacterial changes have one factor in common; the changes 

 only occur in bacteria which are actually growing. He therefore 

 concludes that they must be due to some interference with vital 

 processes at the nascent stage of bacterial growth. On this 

 assumption he proceeds to formulate a working hypothesis 

 which may help to elucidate general principles. The constituents 

 of living bacterial protoplasm have two functions (1) Catalytic 

 i.e., the preparation of food material with the aid of their 

 appropriate enzymes; (2) Synthetic, i.e., the building up of new 

 protoplasm. Any disturbance of the delicately adjusted balance 

 between these two activities, whether by change of environment, 

 pabulum or otherwise, must tend to the production of variants. In 

 his report Dr. Eastwood furnishes a lucid account of the known 

 facts concerning bacterial variants and discusses them in relation 

 to the interesting hypothesis which he has formulated. 



I have the honour to be, 

 Sir, 

 Your obedient servant, 



GEORGE NEWMAN. 

 Whitehall, 



June, 1923. 



