932 
Spontaneous Cancer i Mice. 
By M. Haatanp, M.D., Imperial Cancer Research Fund. 
(Communicated by Prof. J. Rose Bradford, Sec. R.S. Received February 17,— 
Read March 16, 1911.) 
The present paper is based upon observations and experiments made on 
300 mice, obtained in the laboratories of the Imperial Cancer Research Fund 
since the summer of 1908, and in which cancer had developed spontaneously. 
Excluding lung adenomata, lymphomata, and sebaceous adenomata there 
remain 288 mice in which 250 tumours were observed, microscopical 
examination showing that they were to be regarded as true new growths. 
When these tumours were first observed, 7.c. at the time of entering them on 
the laboratory register, 49 of the mice presented multiple tumours, and in an 
additional 77 mice, other subcutaneous tumour-nodules developed at a later 
date. Of the 350 tumours first observed, 42 had a structure quite distinctive 
from that of the well-known mammary tumours of the mouse, and of them 
25 had certainly arisen outside the mamma; 22 were squamous-celled 
carcinomata with marked keratinisation, and of them 14 arose in the 
mammary region, and 8 entirely outside it (jaw. face, vulva, and anus) ; 
5 were sebaceous carcinomata, and of them 3 arose in the mammary region, 
and 2 outside it (anus). 
The remaining tumours were :— 
2 Carcinomata of the preputial gland. 
2 Adeno-carcinomata of the kidney (1 a hypernephroma ?). 
2 
6 Sarcomata (4 spindle cell, 1 round cell, 1 polymorphous cell). 
% i ovary. 
1 Spontaneous “mixed” tumour. 
1 Melanoma. 
1 Fibro-myoma uteri. 
(Not included in the above figures are 30 lung adenomata observed in 
19 mice and cases of lymphomatous tumours.) 
All the other tumours were mammary adeno-carcinomata. 
The observation of typical malignant new growths in different organs 
provides new and additional evidence of a general liability of the tissues of 
the mouse to cancer, 7.e. of an incidence in anatomical sites as varied as in 
man. Their malignant nature was evidenced by their clinical course, their 
recurrence after operation, the formation of metatases, and the results of 
