Inclusion of Carmine Particles by Sarcoma Cells, i i 5 
size. The cells of the primary tumor use up all the specific food 
found in the organism of the host, and the cells transported from 
the primary tumor to other regions of the organism do not find 
the necessary nourishment and consequently can not proliferate. 
Carl Lewin on the other hand thinks that the fact that metastasis 
in these animals takes place only through the aid of the blood 
vessels and not the lymphatics, accounts for the rare occurrence of 
metastasis in these animals. As was shown by M. B. Schmidt 
through his observations on human cancer, blood is capable in a 
majority of cases of destroying cancer cells, found within the 
blood vessels. 
The study of the influence of the blood upon cancer cells 
carried by it and the capacity of such cells to form metastasis 
may serve to clear up a number of phenomena in the genesis of 
cancer. In view of this a systematic study was undertaken by 
the writers on the experimental formation of metastasis, of which 
the present communication forms the first report. 
The experiments consisted in an injection of a tumor emulsion 
into the jugular vein or carotid artery of a white rat, and were con- 
ducted on three different tumors. 
Sarcoma of the White Rat. — This tumor is very malignant, 
grows to a large size, and the occurrence of metastasis after a sub- 
cutaneous inoculation is very rare. In hundreds of animals in- 
oculated by the writers local dissemination was observed not more 
than in a half dozen cases, and once only was metastasis found 
in the liver. An emulsion of this tumor was prepared by cutting 
it in Haaland's mincing machine, grinding in normal salt solu- 
tion and filtering through a layer of coarse gauze. The milky 
opalescent fluid contains a sufficient number of living cells to 
produce a tumor growth after a subcutaneous inoculation. Thirty- 
six rats received an injection of this emulsion into the jugular vein. 
The animals were killed at periods ranging from eight days to 
four weeks after the injection and a thorough search made in all 
the organs for metastasis. Not in a single instance was a metastatic 
tumor found. No microscopical study was made of the organs 
which appeared normal on gross inspection, since this investi- 
gation does not concern itself with the question, where the tumor 
cells circulating in the blood find lodgment, but whether such a 
