508 Scientific Proceedings, Royal Dublin Society. 



and derangement of eell-divisiou closely similar to those which are observed 

 in cancer growth. 



It is now evident that we may find, in this indication of the film, support 

 for our line of reasoning. The substances present in tobacco — probably the 

 intensely alkaline substance nicotine in chief — set up in the cell those 

 same electro-negative conditions which cause or assist it to promote the 

 formation of the latent image, and in this way locally precipitate a state 

 of mitotic instability wliicli from other causes — to be presently discussed — 

 may prevail as a tendency throughout the body cells of the patient. Local 

 mechanical stimuli may contribute. It is, of course, not impossible that 

 in many cases of the kind tlie effect is so far due to the local causes that but 

 for these the cancer would not anywhere have invaded the body. 



An increase in the number of deaths from malignant disease within 

 recent years is admitted by high authorities to be the only conclusion we 

 can draw from the statistics, after every allowance for error has been made.' 

 Modern advances in surgical and medical science undoubtedly enable life 

 to be prolonged in many cases, or even cure to be effected wliere formerly 

 speedy death alone must ensue. This ought to be a set-off against improved 

 diagnosis as a source of error in the statistics. If this increase is a 

 fact, we have to look around for the cause. It is, assuredly, not founded 

 in anything of an evolutionary nature. I say this because if its origin be 

 in the cell itself, a very profound change — profound because seated in the 

 primary organic structure — must be supposed to liave taken place within a 

 few decades. Indeed, if the increase is what we judge it to be from the 

 figures, it has taken place within a single generation, or at most two 

 generations. That quite precludes evolutionary change acting through 

 Mendelian factors. The view that some general body-change is involved 

 appears to be supported by the fact that local causes will initiate the disease 

 in some subjects and not in others. Consequently we must look to some 

 article of diet or some custom of life which can reach and affect the stability 

 of the cell. Tliere are obvious difficulties in laying the blame for a change 

 so deep-seated on a custom. Moreover, we look in vain for any custom at all 

 likely to be responsible. Wlieu, however, we come to the possibilities of 

 •diet, we see much less difBculty. 



In view of what has already been stated, it is legitimate to pursue the 

 matter yet further, and to ask if witliin recent years we are not taking into 

 ■our bodies more abundantlj' than formerly some substance or substances 



^ See "Encyclopsedia Britamiica, " last ed.. Art. Cancer. I find it stated that the recently issued 

 statistics for cancer iu England and Wales (191 2J show the highest mortality as yet recorded. — 

 Da'di/ STail Tear Boole, 1913. 



