100 



p. C. ROLLER, E. LEUCHARS, C. TALUKDAR, AND V. WALLIS 



leukaemia, C3H No. 208 and 210 were the hosts for a second passaged 

 leukaemia. Though the number of cells analysed is not large, the data 

 suggests that the range of variation is reduced, and it was further narrowed 

 in the 6th passage of C3H No. 222. 



loo- 

 se - 



0_ 

 100" 



50- 



0_ 

 100" 



50- 



0. 

 100" 



50 



0. 

 100" 



40 



Ml = 4-4% 



Mi = 0-i% 



Mi = 0-7% 



50 



40 



4 Months 



WCC = 17,900 



No. 251 



40 



Mi = 0-2% 



Mi = 0-5% 



Mi = 0-97o 



n ] r- 



40 



4/2 Months 

 WCC = 40,300 



No. 252 



40 



_1 1 1 L. 



Mi = 0-8% 



liJMM. 



Mi = 0-3% 



Ml = 1-3% 



E^ 



P 



Mi = 1 -270 



Mi = 1-2% 



40 



4% Months 

 WCC = 34,000 



No. 255 



o 



i_ 

 i_ 

 o 

 E 

 I 



o 



CD 



i_ 

 O 



X 



< 





Fig. 1. Primary C3H leukaemia induced by Passage-A vims. 



DISCUSSION 



The presence of a viral agent in mice of the high leukaemic strains has 

 been demonstrated first by Gross (1951) and confirmed by others (cf. Miller, 



