Chemical induction of growth 



abiUty to chelate or affect chelation of heavy metals. Be that as it may, the 

 main point of this communication is achieved when it is recognized, first of all, 

 that these properties reside in a variety of naturally-occurring substances 

 which may have many synthetic parallels, and, second, that in the further 

 elucidation of the relationship between structure and these functions the use 

 of the tissue culture systems, combined with methods that evaluate growth 

 in terms of both cell division and cell enlargement, offer a most fruitful 

 approach to these interesting problems. 



ACKNOWLEDGEMENTS 



The authors wish to acknowledge the help of Miss K. Mears with the 

 sterile cultures and of Miss J. Smith with the cell counts. 



The work has been supported by grants from the National Cancer 

 Institute of the U.S. Department of Health, Education, and Welfare. 



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