482 



On the Action of Radium Bays upon the Cells of Jensen's Bat 



Sarcoma. 



By S. Euss, D.Sc. * and Helen Chambers, M.D. 



(Communicated by H. G. Plimmer, F.R.S. Received March 14, — 

 Eead May 29, 1913.) 



[Plates 12 and 13.] 



The experiments of B. H. Wedd and one of usf have shown that if 

 freshly excised portions of mouse carcinoma are exposed to X-rays or the 

 /3-rays from a few milligrammes of radium for a comparatively brief 

 period (circa 1 hour), the irradiated material will not grow on subsequent 

 transplantation. This line of experimental work has here been extended to 

 Jensen's rat sarcoma, the initial material for which was kindly provided by 

 the Imperial Cancer Research Fund. From several points of view this 

 tumour provides excellent material for the investigations in question. 

 Inoculations are successful in practically 100 per cent., for out of 125 

 inoculations into normal rats, 124 gave growing tumours ; the rate of 

 growth is rapid, tumours measuring 2x2 cm. frequently being obtained in 

 15 days after the inoculation of - l c.c. of tumour emulsion. Spontaneous 

 absorption of the tumours, however, is not uncommon ; five disappearances 

 have occurred in 53 rats, all of which were under observation for a minimum 

 period of 20 days. 



The Inhibitory Effect of Irradiation by (3-Bays. 



Thin slices of rat sarcoma from a rapidly growing tumour were exposed 

 between sterile sheets of mica to the /3-rays from a source of radium, having 

 an intensity of 1*58 mgrm. per square centimetre. Small pieces of the 

 irradiated material were then inoculated into the right axillae of a number of 

 normal rats, into the left axillae of which small pieces of non-irradiated 

 tumour were also inoculated. 



The amount of tumour tissue which can be irradiated in this way is 

 necessarily small and the inoculations were, therefore, made with a 

 hypodermic needle and stilet, the pieces of tumour tissue being as nearly as 

 possible of the same size. 



This procedure was adopted for the same tumour material for three 

 different periods of irradiation, i.e. 30 minutes, T|- hours, and 3 hours, 



* Part of this work was done dining the tenure of a Beit Memorial Fellowship, 

 t ' Journ. Path, and Bact.,' 1912, vol. 17. 



