MALIGNANCY 33 



ignore other very definite phenomena which can with 

 difficulty be brought into line with such views. Moreover, 

 few pathologists will admit that what is seen in cancers has 

 any great likeness to those diseases definitely traced to 

 infection. For such a theory to be complete explanation, it 

 would be necessary to class all inflammatory hyperplasias 

 with malignant overgrowth. It is, of course, impossible to 

 deal with all that has been said in support of the infection 

 theory, which at the moment seems the orthodox view ; but, 

 so far as I have yet discovered, no exposition of it can be 

 reconciled with the complete pathology and histology of 

 these disorders. 1 All the evidence alleged to support it can 

 be interpreted as irritation tending to upset metabolic 

 balance, and the conclusions drawn from it are not com- 

 patible with X-ray cancer, or with the physiological and 

 pathological phenomena at the base of chorion-epithelioma. 

 Such an explanation will, I feel sure, be found a super- 

 fluous luxury, and as such to be dispensed with by the 

 economic philosopher. There are also workers who seem 

 satisfied with the notion that the phenomena in question 

 are due to loss of function in some cells, and increase of 

 function in others. This is no doubt true, but, again, 

 that is the very thing which needs to be explained. 

 We are often told that irritation is the cause of cancer, 

 and the mere statement seems to be considered ex- 

 planation. This is not the case for, though irritation is 

 often followed by cancer, all that is proved is that in some 

 of the organisms concerned resistance to irritation is 

 weakened, whereas in others it is maintained. Not every 

 clay-pipe smoker, even with syphilis, or every burnt 

 Kangri-user in Kashmir, or every chimney sweep, or pitch 

 or paraffin worker, gets cancer. We wish to know why 



1 See Appendix A. The Infection Theory of Cancer. 

 3 



