12 Faraday, Biological Aspect of Cancer. 



history and to retain only their fundamental vitality, 

 limited as to form, but intensified in individual vigour. 



What can be more remarkable than the fact that the 

 presence or absence of a particular gas in a free form 

 determines, not the life of a plant, but whether it shall re- 

 produce by mere cell division or by the wonderfully complex 

 process of yielding spores or seeds, which contain in an 

 altered form the possibility of reproducing the parent ; or 

 that the presence or absence of light shall determine 

 whether a leguminous plant shall produce yards of mere 

 mycelium, or the extraordinary variation, elaboration, and 

 co-operation of inflorescence and fertilisation ? 



The successful application of oxygen in cases of 

 pneumonia is also suggestive. In these cases oxygen is 

 applied for the purpose of maintaining the blood in good 

 condition and keeping up the action of the heart, in other 

 words the method is to do artificially what the lungs, 

 through the progress of the disease, have become incapable 

 of spontaneously doing. But it ought not to be over- 

 looked that this artificial application appears not only to 

 do the work of the lungs during their state of incapacity 

 but to stop the progress of the disease itself, thus 

 restorins: the lungs to a normal state. 



Note, August 7th, ifcigg. — Since the foregoing paper was 

 set up in type my attention has been directed to the fact that 

 Cohnheim's hypothesis (with which I was not previously 

 acquainted), that morbid growths of the nature of cancer may 

 arise from minute portions of embryonic tissue which have 

 persisted in an undeveloped state amongst the mature tissues, 

 in some respects seems to be related to the hypothesis I have put 

 forward. With reference to this and other previous suggestions and 

 investigations, I wish to say that there are differences in detail, 

 and more especially in the point of view, which have appeared 



