THES SrUDY OF CANCER 25 
a transplanted tumour is growing proceeds only from the con- 
sequences of growth, and the demands made for nutriment ; 
but as a rule the mice look quite well, and malnutrition 
progressing to wasting is an occasional and accidental 
occurrence. 
Thus far I have considered only the growth of cells, but 
we have to deal with the growth of tumours often weighing 
nearly as much as a mouse. If cell nutrition is so important 
it may seem strange to say that the mice usually enjoy perfect 
health. It was necessary to ascertain if the nutritive balance 
in an animal had been disturbed by the presence of a tumour 
in any other way than could be indicated by iil-health and 
wasting. When very young mice are made to bear rapidly 
growing and large tumours, they often only attain about half the 
weight of others of corresponding age. When adult animals 
bear rapidly growing and large tumours they may lose weight, 
and more than is accounted for by the weight of the tumour. 
This they speedily make good when the tumours are removed, 
and the mice then revert to the normal conditions without any 
detectable sign of their having ever borne tumours. The 
gastric contents of normal mice after successful inoculation 
with tumours contain a large excess of HCl during active 
digestion, as observed by Cramer and myself, and demonstrated 
by Copeman and Hake, who have analysed the stomach contents 
of over five hundred mice. This increase in HCl is not to be 
considered as out of accord with clinical observations in the 
human subject. There is much evidence, recently added to by 
the careful investigations of B. Moore, that the HCl is diminished 
in patients suffering naturally from cancer. I am at present 
considering the facts on the growth of cancer in mormal mice. 
We require more data regarding mice spontaneously affected 
with cancer. The contradiction between the state of affairs in 
normal mice artificially made to bear tumours, and patients 
bearing them naturally, reinforces the warning I have expressed 
already. The conditions of the growth of cancer are to be 
sharply distinguished from the conditions of origin, and I have 
also pointed out that the conditions of growth in mice naturally 
cancerous, and in normal mice, differ from one another. The 
contradiction above referred to is probably only apparent, and 
when it is resolved we may know much more of the deeper 
significance of the diminution in HCl in those spontaneously 
