14 PREFACE 



agents, because certain substances were described 

 as influencing the development of the eggs of 

 certain fishes long before we induced human 

 cell-division. But the work w^ith human cells 

 and the isolation of the actual chemicals is new, 

 as well as the deduction from this work that 

 normal cell-division is brought about by cell- 

 death. 



Provided our interpretations are correct, we 

 have the field of research and methods for trying 

 to find substances which will inhibit the action 

 of the normal and of the "augmenting" agents 

 which excite physiological and malignant division 

 of individual cells. Moreover, we hope to be 

 able to isolate the organisms whieh produce the 

 augmenting substances, and to try to deal with 

 them. 



The experiments to be described were carried 

 out in a laboratory of the Liverpool School of 

 Tropical Medicine 



The illustrations were kindly painted for us 

 from the specimens by Miss E. H. Barry. 



H. C. Ross. 



26, CLARQES STREET, W. 



