170 APPLICATION TO CANCER RESEARCH 



in reality causes localized cell-death, and the cause 

 of the proliferation due to irritation would in all 

 probability be found to be due to the same cause or 

 causes which make our cells multiply in order to heal 

 up a cut or a sore. 



Now, there can be no doubt that cancer occurs in 

 sites where there has been previously some form of 

 chronic irritation, and cancer is another name for 

 malignant proliferation of cells. Since such irritation 

 is probably directly associated with the cause of the 

 cell-proliferation of healing, we made our first endea- 

 vours to try to find out this cause of cell-reproduc- 

 tion in the body, for it was considered that if that 

 could be found a step in the right direction would 

 be made. Some attempts at healing are always going 

 on in the parts that are subject to chronic irritation, 

 and we may safely say that the cell-proliferation of 

 healing is going on in these parts. Cancer super- 

 venes on old ulcers and sores, which, of course, are 

 healing sites. In the breast and uterus, two of the 

 commonest places for cancer, the cell-proliferation of 

 healing occurs every month during the ages of actual 

 sexual function, and at the climacteric a large involu- 

 tion takes place, accompanied by destruction of tissue. 

 The irritation which causes cancer of the lip is usually 

 the pressure of a tobacco-pipe; X-ray cancer usually 

 follows the ulceration and damage due to burns; and 

 there are many other examples. The cause of the 

 cell-proliferation of healing, therefore, constituted our 

 first investigation in the path of cancer research. 

 V / Leucocytes and lymphocytes are the cells which pro- 



