210 Dr. Bashford and Messrs. Murray and Bo wen. [May 30, 



first tumour (1), inoculated after 10 days' growth, the results were completely 

 negative, no tumours developing. A tumour (2) was preserved entire after 

 10 days' growth, and showed the histological features of spontaneous 

 absorption, while another (3) transplanted on the same day with the same 

 histological appearance gave 11 per cent, of success. Five tumours (6 to 10) 

 of large size which were not interfered with disappeared spontaneously. 

 Two tumours (4 and 5) continued to increase in size, in each case attaining 

 half the weight of the mouse in which they were growing. They were 

 almost entirely necrotic, but the healthy portions on being transplanted gave 

 63 per cent, of tumours in each case, both had apparently recovered from the 

 negative phase fatal to those spontaneously absorbed and causing a negative 

 result, or low percentage of success in those transplanted after 10 and 

 16 days' growth respectively. This one experiment presents all the 

 phenomena, usually only revealed by a study of several consecutive series. 

 The protocol should be compared with that of experiment 50 Z, given on 

 p. 211. The close genealogical relationship of these two experiments so 

 strongly corroborative of each other is shown in the chart, fig. 4, p. 206. 

 If followed backwards, both are seen to arise from tumours of series 47 L, 

 a descending " side-branch " on the " ascending stem " described on an earlier 

 page. 



From a review of the observations recorded in the preceding pages we 

 conclude that the proliferation is only apparently continuous. In reality it 

 is made up of a succession of alternating phases of increased and diminished 

 energy of growth. 



In the preceding pages we have concerned ourselves solely with estimates 

 of the power of proliferation throughout a long time, although the extent to 

 which cell degeneration goes hand in hand with cell proliferation is remark- 

 able (see two following protocols and table of experiments on pp. 216 and 

 217). Growth is always accompanied by extensive degeneration of the cells 

 of the tumours. The histological examination of all the tumours propagated 

 has been systematically performed, and shows that, just as all the cells are not 

 equally capable of continuing growth, so all are not histologically identical in 

 any tumour. The histological difference most easily observed is that rapid 

 and complete degeneration which attacks the central areas of the alveoli in 

 which the parenchyma cells are arranged. 



Transplantation 50, Series Z. 



Parent tumour. Young brown female of Generation 49, Series F. Tumour 

 weighed 5 - 65 grammes. Mouse alone weighed 9 - 3 grammes. Two tumours 

 in medial line of back. Anterior practically completely necrotic with thin 



