CONDITIONS INDUCING OVERGROWTH 295 



vegetative activities of the cell are called into play to utilize 

 that material in proliferation ; or (2) that the irritation be of 

 such an extent and continued for so long a period, that in con- 

 sequence of the increased functional activity of the cell, of the 

 increased secretion, and the increased blood and lymph brought 

 to the part, the relationships of the cell to those in its immediate 

 neighbourhood are altered to such an extent that, while there is 

 adequate or even increased assimilable material which it can 

 absorb, the very alteration of environment and the increased 

 tension to which it is subjected hinder the proper performance 

 of function, and the stored-up energy becomes diverted from 

 the performance of specific function to proliferative activity. 



Now, considering the first condition, the very property of 

 inertia must be a preventive of sudden change from the functional 

 to the proliferative stage of the cell, while again, the environment 

 of the cells continuing relatively unaltered, they must easily 

 respond to the recurrent stimulation to perform their normal 

 functions, and responding, the tendency to multiply must be 

 liable to arrest. Thus I am inclined to consider that while this 

 condition may be possibly in action to induce that moderate 

 and orderly amount of overgrowth which follows upon increased 

 tissue activity, it is incapable of inducing or explaining neoplasia. 



A STAKTING-POINT COMMON TO ALL FORMS OF TUMOUR 



It is the second state, or condition, that affords the starting- 

 point for excessive local overgrowth in previously normal tissues. 

 And, accepting this view, we at last reach the position of obtain- 

 ing one common starting-point for all forms of tumour proper. 

 This starting-point is that condition in which the cells of the 

 part, whether functional or lying latent, upon being stimulated 

 and as a consequence undertaking active assimilation and 

 anabolism, cannot from their relations carry on their peculiar 

 functions to a corresponding extent, so that the accumulated 

 energy is instead utilized in mitotic changes and cell division, 

 rather than in the normal katabolism. 



Herein, however, we do but explain the first stage in the 

 development of a tumour proper. How is it that once started 

 the cells continue to proliferate ? What are the conditions 

 under which we can recognize and explain the development of 



