6 Faraday, Biological Aspect of Cancer. 



Assuming, then, the first stage to be merely the exertion 

 and stimulation of the inherent property of cell multi- 

 plication,with arrested differentiation into (let us say) blood 

 channels and nerves, the complete renewal of the cir- 

 culating and nerve systems of the subject being thus 

 locally interrupted, with consequent disturbance to the 

 general health, and a certain isolation of the affected part 

 (like a secret society of malcontents in a State), how do 

 the new cells acquire a parasitical character ? An ex- 

 planation may possibly be found in what we know of 

 microbe life. Zymotic diseases are generally attributed 

 to the actual invasion of the body of the sufferer by a 

 previously existing pathogenic microbe, and cancer itself 

 has been declared to be probably infectious and to be due 

 to a pathogenic organism. The views which I am en- 

 deavouring to develope are not inconsistent with these 

 hypotheses. The immediate question is merely that of 

 the evolution of the micrococctts and of its malignant 

 character. 



I have long held the opinion — as being most consistent 

 with the phenomena of the appearance and disappearance 

 of epidemics and with Pasteur's attenuation experiments — 

 that pathogenic microbia are, to begin with, harmless or 

 even benignant saprophytes or organised ferments, which, 

 through changes in the environment, have been compelled 

 to take up a parasitical or malignant character in obedience 

 to the law of the struggle for existence. In a paper read 

 at the meeting of the British Association in 1882,* I based 

 on Pasteur's discovery of the attenuating influence of free 

 oxygen on pathogenic microbia, and on the vastly increased 

 destructiveness, or fermenting power, of the harmless yeast 

 plant when cultivated in deep vats — which are speedily 



* Report of the Fifty Second Meeting of the British Association, held at 

 Southampton in August, 1882, p. 578. 



