206 



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



to diminished transplantability ultimately affects the descendants of the 

 tumours which had previously escaped it, and hence appeared to constitute 

 an ascending main stem in the graphic record. We have always obtained 

 a rise to a maximum which cannot be maintained, and a subsequent fall 

 which is also not permanent if continued propagation be possible. Up to 

 the present we have encountered no exception to this rule in more than 

 600 series of inoculations with this tumour, and the rise to a maximum with 

 a subsequent fall has been repeated 50 times in simultaneous series of 

 experiments. If the subsequent behaviour of the descendants of several 

 of the daughter tumours from any one batch of inoculations be followed, 

 successive maxima are seen to arise one after another at short time-intervals. 

 The maximum percentage of success of the experiments as a whole is 

 maintained continuously at a high level between 70 and 90. Each strain, 

 after reaching its maximum, falls and makes way for another which had 

 previously presented a lower percentage, and, after attaining a maximum, in 

 turn falls. A high percentage is thus maintained by successive maxima 

 developing in parallel series of experiments. 



IOO r 



570 COG 050 7UO 750 800 850 DAYS 



Fig. 4. — Graphic record of results of further propagation of two tumours of an experi- 

 ment in which 32 per cent, of the animals developed tumours (47 L). Both of 

 these gave an increasingly higher percentage of success till a maximum 

 (50 Z and ii 50 C) followed by a fall was again obtained. The dotted lines are 

 not completed to the point at which they should end, but merely indicate the 

 downward direction of the curve. The details of the fall following the 

 maximum 50 Z are given in the preceding graphic record fig. 3. 



The preceding diagram shows clearly the manner in which successive 



maxima develop. The subsequent behaviour of two tumours of one of the 



