Action of Radium and X-Rays upon Tumour Growth. 127 



A reduced rate of growth changes into a rate which appears slightly quicker 

 than that of the untreated tumour. This latter phenomenon will be referred 

 to again in Section C. 



It will be seen from the data in Table I that the lethal dose is about 

 thirty-five minutes, only one animal out of twelve bearing a tumour, when 

 the cells had previously been irradiated ; normal tumour inoculated into the 

 left axillje of the same animals grew in every ease. 



The lethal dose for the two other varieties of tumour already referred to 

 has been found by following a similar method to that just outlined. 



It is not possible to express the results of these experiments in quite the 

 same way as for the Jensen's tumour, because they do not give 100 per cent, 

 of growing tumours when inoculated. The rat carcinoma is very difficult to 

 propagate, rarely as many as 50 per cent, of the inoculations into normal 

 animals resulting in tumours. 



The subjoined two charts illustrate the results obtained upon two series of 

 animals. The tumours depicted in the charts are drawn to scale, the time 

 being fifty-six days and twenty-seven days respectively after inoculation. 



