16 Mr, J. C. Mottram and Dr. S. Russ. Susceptibility and 



ZZ JO DAYS 7 



If. 



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<m 



•f <z> 



Z ^ 

 3 '>o 



D 



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Fig. 11. — A. Tumour only ; B. Tumoui' + Normal spleen ; C. Tumour + Spleen of tumoui'- 

 bearing animal ; D. Tumour + Immune spleen. 



Tumour Treated with Spleen Extract, Serum, and Plasma of Immune and 

 Normal Bats hefore Inoculation. 



The method of experimentation on these lines was to mix an emulsion of 

 sarcoma cells with either of the above liquids, and after a certain lapse of 

 time to inoculate the emulsion into normal rats. 



The spleen extract was prepared by pressing normal and immune spleens 

 in a Buchner's press. 



The result of a number of experiments on 102 animals on these lines 

 showed that there was no decided effect upon the subsequent rate of growth 

 of the sarcoma cells. 



Part II. — Microscopic Observations upon Grafts and Tumours. 



Side by side with the experiments whose description forms Part I of this 

 paper, microscopic studies have been made of the early stages of growth. 

 These observations upon grafts were carried out in order to determine the 

 reactions of the tissues of the host, and the immediate behaviour of the 

 sarcoma cells, when inoculated under varying experimental conditions. 



