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



90%. 



7JO BOO 850 900DAVS 



Fig. 9. — Graphic record of a strain of 13 successive transplantations at short intervals 

 The fluctuations already described appear in this series also. 



gives the results of rapid passage from animal to animal from the 46th to 

 the 58th transplantations. This series of experiments was rendered possible 

 by the rapid growth of certain tumours arising at each subinoculation. 

 So far from resulting in a progressive increase in transplantability, the 

 55th transplantation presents the lowest percentage in the whole series. 

 The fluctuations already described for other strains are present here also, 

 when the interval between successive subinoculations is shortened to 

 intervals of 8 to 15 days. Such a curve, representing a succession of rapid 

 transplantations, is a special case like those depicted in the curves* we 

 have already published. 



In the preceding pages it is assumed (1) that the conditions have been 

 sufficiently uniform throughout the experiments to exclude fortuitous 

 fluctuations, and (2) that the percentage of success on transplantation 

 furnishes a reliable measure of power of proliferation. If the precautions 

 we have taken warrant these two assumptions, we are entitled to conclude 

 that the fluctuations in proliferative power revealed are natural features of 

 the growth of Jensen's tumour in English mice. They are due to the 

 * ' Second Scientific Report of Imperial Cancer Research Fund,' Part II, p. 54. 



