214. Dr. Bashford and Messrs. Murray and Bowen. [May 30, 



increases, would then merely indicate the elimination of degenerating 

 tumour cells by the selection exercised at transplantation and the further 

 elimination occurring in the days immediately following. Tumours are 



40 I 41 P 42 L 43 L 44 D 45 C 46 G 47 H 48 E 49 C 50 L 51 L 



15% 20% 23% 30% 53°/ 53% 66% 78% 84% 37% 27 / o 27% 



Fig. 7. — Diagram to illustrate the way in which the elimination of degenerating cells by 

 repeated transplantation may result in a progressive increase in the percentage 

 of success in a strain of transplantations. Each large square represents the 

 constitution of the parent tumour of the batch of inoculations whose label is 

 printed above it, as measured by the percentage of success printed below. 

 One hundred inoculations are supposed to be made in every case, and the 

 number of small squares left clear, corresponding to the percentage, shows the 

 number of fragments which developed into tumours. 



ultimately obtained free from the original admixture of such doomed cells. 

 They consist entirely of the progeny of those healthy cells (in the first 

 tumour of the series) which were destined to carry on growth. Even the 

 progeny of those healthy cells ultimately enters upon a degenerative phase, 

 as is shown by the sudden reappearance in the diagram (49 C) of a large 

 blackened area when the clear area has attained a maximum. The increased 

 tendency to degeneration reappears over a considerable interval, as a further 

 reduction of the clear area in the diagram at 50 L and 51 L indicates. 

 Thus the tendency to degenerative changes is intercalated in the course of 

 the continued proliferation of the parenchyma cells. 



Our methods of propagation and of recording the results enable us to 

 analyse the growth of small groups of cells. So far as the descriptions of 

 experiments published permit us to form an opinion, other investigators have 

 emulsified single tumours, or have emulsified and mixed several tumours, and 

 injected portions of the emulsion. This method maintains a mixture of 

 strains at each inoculation and they have therefore recorded the results as 

 average percentages of all subinoculations made after the same number of 

 transplantations, no detailed analysis of the features of growth being 

 attempted. Other authors, therefore, do not give the details of the 

 behaviour of single strains, and we are unable to compare their results with 

 our own. The increase in the percentage of success in our later transplan- 

 tations as compared with the earlier ones obtained by Jensen himself must 

 not be confounded with a permanent alteration in the character of the cells 

 as the result of the number of transferences from animal to animal. The 



