130 Drs. S. Russ, H. Chambers, and Miss G. M. Scott. 



Table III. 





Interval 

 before 

 inoculation. 



Number 

 of 



animals. 



Volume of tumour com- 

 pared with that of controls. 





Period of 

 irradiation. 



Time after inoculation. 



Remarks on tumour 

 growth. 









2 weeks. 



3 weeks. 



4 weeks. 





4 weeks 



28 days 



18 

 X-rayed 



26 

 controls 



0-77 



-46 



0-40 



X-rayed animals grew 

 4 progressive tumours. 



14 disappearing tumours. 

 Control animals grew 



12 progressive tumours. 



14 disappearing tumours. 



6 freaks 



13 days 



9 



X-rayed 

 10 



controls 



65 



0-44 



— 



X-rayed animals grew 



3 progressive tumours. 



6 disappearing tumours. 

 Control animals grew 



9 progressive tumours. 



1 disappearing tumour. 



8 weeks 



11 days 



21 

 X-rayed 



20 

 controls 



0-42 



-40 



0-35 



X-rayed animals grew 

 7 progressive tumours. 

 14 disappearing tumours. 

 Control animals grew 

 14 progressive tumours. 

 6 disappearing tumours. 



12 weeks 



13 days 



29 

 X-rayed 



24 

 conti-ols 



0-84 



0-76 



0-6o 



X-rayed animals grew 

 19 progressive tumours. 

 10 disappearing tumours. 



Control animals grew 

 17 progressive tumours. 

 7 disappearing tumours. 



(C) The Effect of the Rays in Various Bases %i'po% Animals which are Bearing 



Tumours. 



Here we have to distinguish between three varieties of exposure : — 



(1) Exposures in which the animal does not share to an appreciable extent 

 in the radiation that the tumour receives^ i.e., a localised exposure to beta-rays. 



(2) Exposures in which the tumour does not share in the irradiation of the 

 animal, i.e., tumour screened from the rays. 



(3) Exposures in which the animal shares in the radiation that the tumour 

 receives, i.e., a generalised exposure of X-rays to the whole body. 



(1) Localised Exposures. — If a small superficial tumour exists in the animal 

 body, it is possible, by the use of easily absorbed rays, such as beta-rays, to 

 expose the cells of the tumour without the rest of the animal sharing to an 

 appreciable degree in the radiation. 



A series of experiments upon a number of animals was carried out on the 



