200 



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



numerous as time goes on, spreading out like the branches of a tree from 

 any tumour selected as a starting point. On the basis of this relation a 

 genealogical tree of all the transplanted tumours has been constructed in 

 which the intervals of time between successive transplantations are also 

 recorded. This result is achieved by measuring the number of days since 

 propagation commenced and marking the respective dates of transplantation, 

 so as to mark off abscissae ; the power of proliferation being measured by 

 marking the percentage of successful implantations as ordinates. The point, 

 determined by these two variables for every tumour transplanted, records its 

 power of proliferation and the date of transplantation. 



When the point so obtained from any one tumour at the end of the series 

 is connected by a line with the point similarly obtained for the tumour from 

 which it was derived, and the connections followed backwards through the 

 corresponding points of the preceding transplantations, the absolute duration 

 of propagation and the steps in the lineage of the tumour at the end of the 

 series can be seen at once. As the process of connecting up the points is 

 continued backwards the lines from the points obtained for other strains 

 converge and coalesce till all ultimately unite in the point obtained for the 

 percentage of success attending the primary transplantation of the sporadic 

 growth. 



The graphic records accompanying this paper are small portions of a large 

 chart recording in this way the results of all our experiments with Jensen's 

 tumour extending over a period of two and a-half years. 



For the purpose of recording the experiments each batch of implantations 

 performed with one tumour is labelled with a number, stating the number of 

 successive transplantations from the beginning of the series. For example, 

 the parent tumour of a batch of implantations belonging to the 40th trans- 

 plantation has been obtained after 39 successive transferences to fresh mice. 

 To distinguish between several batches, the parent tumours of which have 

 been obtained after the same number of transferences, a letter of the 

 alphabet is added to the number of the transplantation. The genealogy of 

 the various series of implantations is not indicated by this nomenclature, 

 and for this purpose the graphical records, now to be described, have been 

 devised. 



As it is important that the exact meaning of this graphical record should 

 be clearly understood, the method by which it is built up may be exemplified 

 by a special case (fig. 1) forming part of another chart (fig. 2). 



(1) On the 739th day of propagation, a tumour of Transplantation 45, 

 Series C, was transplanted into 52 mice which were labelled 46 C ; 32 mice 

 died in the first 10 days after transplantation. In the remaining 20, 



