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THE ORIGIN OF THE 

 PLANT TUMOR CELL* 



Arniin C, Braun 



THE ROCKEFELLER INSTITUTE 



One of the most striking characteristics of higher animals and plants is 

 the extraordinary way in which all of their functional parts fall into a 

 coherent, flexible, but definitely limited pattern. This harmony of struc- 

 ture and function is a reflection of organized and self-regulated growth 

 and development. Sometimes, however, a relaxation of the orderly 

 control of cellular growth occurs. This is never more dramatically illus- 

 trated than in the so-called cancerous diseases, for here the character- 

 istic feature of the disease is the breakdown of the restraining influ- 

 ences that govern so precisely the growth of all normal cells within an 

 organism. The question of what governs the growth of normal cells 

 and what is entailed in overcoming those restraints under conditions 

 of neoplasia is fundamental and constitutes the ultimate basis of the 

 tumor problem. It is with that problem that we should like to concern 

 ourselves at this time. 



A century of experience has demonstrated that a tumor cell is an 

 altered, more or less randomly proliferating cell which reproduces true 

 to type and against the growth of which there is no adequate control 

 mechanism in a host. This cell type has acquired, as a result of its 

 alteration, a capacity to direct its own activities largely irrespective of 

 the laws that govern so precisely the growth of all normal cells within 

 an organism. Since the tumor cell is an altered cell, it might be appro- 

 priate to inquire briefly into the nature of the agencies responsible for 

 the cellular change. In considering this aspect of the tumor problem, 

 one is forcefully struck by the multiplicity of diverse agencies that have 



* This investigation was supported in part by a research grant (PHS C-2944 

 MirG) from the National Cancer Institute. 



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