PREFACE 



THE experiments described in the following papers 

 were begun in January 1913, and they form part 

 of the general researches of the John Howard 

 McFadden Research Fund into the causation of 

 cancer and other forms of cell-proliferation. These 

 researches have already been described in detail in 

 the preceding volumes. They include a working 

 hypothesis that normal cell - reproduction and 

 benign tumours are caused by certain chemical 

 agents, called auxetics, such as tyrosin, creatin, 

 etc. ; and that cancerous tumours are caused by a 

 mixture of auxetics with another group of sub- 

 stances, called kinetics or augmentors, such as 

 choline and cadaverine. Auxetics are produced in 

 the body by cell-death as the result of injury ; 

 kinetics are decomposition products produced by 

 the action of bacteria and other organisms. The 

 former volumes contain many experiments made in 

 the endeavour to prove this hypothesis, but those 

 experiments were mostly made with human and 

 other animal cells ; in the present volume, how- 

 ever, we have not touched on the immediate cancer 

 iv 1* 6 



