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The Experimental Analysis of the Growth of Cancer. 



By E. F. Bashford, M.D., J. A, Mukray, M.B., B.Sc, and W. H. Bowen, 



M.S., F.K.C.S. 



(Communicated by Professor J. Eose Bradford, F.R.S. Received May 30, — 



Bead June 14, 1906.) 



In the present paper we shall attempt to analyse the growth of cancer 

 when propagated artificially in mice, mainly on the basis of 25,000 inoculations 

 of Jensen's tumour performed in conjunction with Dr. W. Cramer on behalf 

 of the Imperial Cancer Research Fund ; but also with reference to inoculations 

 made with 32 other mouse tumours during the past three years. Although 

 the question of the continuous or interrupted na.ture of cancerous proliferation 

 is of fundamental importance, both from the standpoint of the ultimate 

 explanation of the nature of the disease, and from the standpoint of its 

 treatment, such an analysis has never been attempted before. It has been 

 assumed that the growth of cancer is vegetative, as inexplicable as any other 

 form of growth, only to be partially understood by an elucidation of the 

 processes by which normal tissues become cancerous. Artificial propagation 

 enabled us to submit this assumption to the test of experiment, and imposed 

 the necessity of determining by direct observation whether propagated cancer 

 exhibited a mode of growth throwing light on the nature of the disease and 

 the apparently continuous proliferation of sporadic tumours. While the 

 experimental propagation of cancer may reveal new facts with a bearing on 

 the nature of the disease it also affords opportunities for rational and 

 empirical therapeutic experiments, and adequate opportunity for controlling 

 the results. These two purposes have been constantly kept in view in our 

 investigations. 



When a number of animals are inoculated with a transplantable mouse 

 tumour, all do not develop tumours and the tumours which do develop are 

 not all of the same size after the same interval. In order that propagated 

 cancer might be available for the second of these purposes it was necessary 

 to find out what influence the variable conditions of experiment exerted on 

 the proliferation of the cells. In the course of these preliminary studies facts 

 bearing on the nature of cancer have also been ascertained. 



Irregularities in the rate and amount of growth are introduced by (1) 

 Transference from one race of mouse to another even when nearly allied : 



(2) Transference from young to old mice of the same race or vice versd : 



(3) Variations in the site of implantation of the cancerous tissue : (4) Varia- 

 tions in the amount of the tissue implanted and in the manner of introducing 



