1906.] Experimental Analysis of the Growth of Cancer. 



215 



highest percentage of success obtained by Jensen* is given as 66 per cent, 

 for single experiments. We recorded in March, 1904,f success in 90 per 

 cent, of the animals used at the third transplantation into English mice. 

 Since then we have repeatedly obtained from 80 per cent, to 100 per cent, of 

 success in individual strains in the manner already described. The varia- 

 tions in percentage of success appear to be quite irregular when recorded 

 in tables giving either the average percentage of success for the successive 

 series of transplantations, or the results of individual experiments in each 

 transplantation (see Table on pp. 216 and 217). The confusion presented led 

 us to study the percentage of success in greater detail in single strains, with 

 the result that the irregularities resolved themselves into the orderly 

 sequences we have described. 



The experiments we have already described, and the graphic records 

 pertaining to them, have enabled us to follow the behaviour of single strains 

 in the direct line of descent. The phase of growth brought out by maximal 

 success on transplantation is the same in separate strains if the fluctuations 

 have any meaning at all. In the same way the minimal success represents 

 the opposite phase of growth. In the accompanying graphic record (fig. 8) 



Fig. 8.— Graphic record to show that the same stage of proliferative activity is not always 

 reached after the same number of transplantations. (Repetition of fig. 3.) 



the minimum is reached after one transplantation in Experiments 51 V. 

 51 W, 51 iiA, 51 iil, and 51 iiJ ; after two in Experiments 52 T and 52 U ; 

 * ' Centralblatt f. Bakt.,' vol. 34, 1903. 



t ' First Scientific Report of Imperial Cancer Research Fund,' p. 14. Cf. also 'Second 

 Scientific Report,' pp. 22 and 54. 



