294 ON GROWTH AND OVERGROWTH 



energy becomes utilized in another direction namely, that of 

 multiplication. 1 



Here we arrive at the strongest objection to the " cell rest " 

 theory pure and simple of tumour growth. It is one thing to 

 have " cell rests " and foetal remains present in the various 

 parts of the body, quite another thing to have tumour growth 

 originating in these. It is probable that the vast majority of 

 " cell rests " never take on an excessive purposeless growth. 

 " Cell rests " may show signs of active proliferation from the 

 first ; they may, on the other hand, lie latent for long years, 

 only then showing tendencies to excessive overgrowth ; lastly, 

 they may never be found in other than what I may term " a 

 resting stage." So that, granting the existence of " cell rests," 

 we cannot grant that these misplaced cells are the primary cause 

 of tumour formation at most they are a predisposing cause ; 

 some other cause a something acting upon the " rests " is 

 necessary to explain their aberrant and excessive growth. We 

 have to demand some change in the surrounding conditions. 



CONDITIONS NECESSARY FOR CELLULAR HYPERPLASIA 



Keeping in mind these two conceptions, namely, that the 

 stimulus to increased functional activity comes from without, 

 and that the cell in its actions exhibits marked inertia, we can 

 thus realize the conditions under which increased cell proliferation 

 may be excited in a tissue, whether normal or containing mis- 

 placed elements. These conditions are either : (1) that the cells 

 be subjected to periodic irritation leading to increased functional 

 activity, increased secretion, etc., followed by periods of rest in 

 which there is storage of cell material to such an extent that the 



1 Along these same lines we best explain the proliferation of mother cells 

 in functioning tissues ; though these give rise to fully active cells, their rela- 

 tionships lead them to live a vegetative existence. Alterations in their sur- 

 roundings brought about by increased activity of the surrounding daughter 

 cells must tell upon their relationships, and altered tension and environment 

 must here again lead to the same reactive increased anabolism, and this must 

 initiate cell division. Where again we have cells once functionally active 

 becoming through senile changes latent and somewhat atrophied, here also any 

 stimulus, whether mechanical, chemical, or physical, acting upon those cells 

 and calling for increased activity, may in like manner render those cells pecul- 

 iarly liable to proliferate. The change of relationships in the cells brought 

 about by their atrophy and the somewhat altered relationships of the surround- 

 ing parts may render them incapable of performing their normal functions, and 

 increased anabolism may be followed instead by multiplication. 



