DEVELOPMENT AND ENVIRONMENT 63 



experiments. When lymphocytes from the peri- 

 pheral blood or elsewhere are placed on a suitable 

 jelly containing auxetics and incubated they 

 divide they must divide. But erythrocytes will 

 not divide until they have reached a certain 

 development. Therefore another factor is re- 

 quired for them in addition to the presence of 

 auxetics it is maturity. Unless a cell is mature 

 it will not divide. But if the erythrocyte is 

 mature and is placed under the power of an 

 auxetic it will indeed must divide. 



Lastly, it must be realised that the serum in 

 which they are bathed has the power of retaining 

 the height of the coefficient of diffusion of blood- 

 cells ; and this power seems to be dependent 

 upon the salt content of that serum. The co- 

 efficient of diffusion of a certain cell therefore 

 varies, within certain limits, with its environment, 

 and the variation of the environment seems to 

 be the variation of its density. 



REFERENCES 



(1) Induced Cell- Reproduction and Cancer, Hugh C. Ross and 

 J. W. Cropper. Murray : London, 1910. 



(2) "A Report on Cancer Research," Hugh C. Ross and C. J. 

 Macalister. The British Medical Journal, October 23, 1909. 



(3) " The Coefficient of Diffusion," H. C. Ross. Proceedings of the 

 Royal Society. B. Vol. 81, 1909. 



(4) " On the Death of Leucocytes," H. C. Ross. Journal of Physi- 

 ology, September 1908. 



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