THE SLOP OF sCANCER 7 
took definite shape on the basis of a scheme of research sub- 
mitted to the Executive Committee by myself in October, 1902, 
and diligent search was instituted into the occurrence of cancer 
not only in all races of mankind, civilised and aboriginal, but 
also throughout the animal kingdom. A farm was secured for 
observations on the larger domesticated animals suffering 
naturally from cancer, and every opportunity was utilised of 
testing the possibility of transferring the disease and studying 
it under experimental conditions. The scheme of experimental 
research, thus embarked on, received an unexpected justifica- 
tion and a great impetus by the publication of Jensen’s accurate 
and fundamental observations on the inoculation of a tumour 
of a mouse in 1903, and contemporaneously of those of Borrel. 
Since then valuable work has also been done by Apolant, 
Haaland, Loeb, Michaelis, Henke, and, above all, by Ehrlich. 
Jensen’s great service consists in the fact that he did not 
restrict himself to demonstrating the reproduction at the site 
of inoculation of the features of the original growth. He also 
proved,' by carefully following the processes at the site of 
inoculation step by step, that the new formation was due to 
the continued growth of the cells peculiar to the tumour, parts 
of which he had introduced. Jensen’s work has been energeti- 
cally followed up in all civilised countries, and in the first 
instance in the laboratory of the Imperial Cancer Research 
Fund. 
The investigations of Murray and myself on an adeno- 
carcinoma: mammz and Jensen’s own tumour confirmed his 
observations, and, by extending them to a large number of other 
malignant new growths in mice, established the experimental 
study of cancer on a secure foundation; so that, after some 
preliminary controversy, it is now universally agreed, infection 
plays no part in the process of experimental transference. On 
the contrary, transference to fresh mice merely affords the cancer 
cell an opportunity for continuing to proliferate in fresh soil. 
With Murray I made an exhaustive study of the processes at 
the site of the inoculation of cancerous tissue in the case of 
1 This demonstration is sometimes erroneously attributed to L. Loeb, who 
obtained tumours on inoculating sarcoma in rats in 1Igo1-3. Loeb’s original 
description of the processes at the site of inoculation does not bear this interpreta- 
tion. He also admitted the possibility of the tissues surrounding the grafts 
acquiring sarcomatous properties. 
