114 
Scientific Proceedings (43). 
cytoplasm. These granules are round, of very constant size and 
are stained pink by the carmine. They occupy the entire cyto- 
plasm. By means of Altmann's fixative and stain exactly similar 
granular pictures are obtained. 
70 (595) 
The formation of metastases after an intravascular injection 
of tumor emulsions. 
By I. LEVIN and M. J. SlTTENFIELD. 
[From the Department of Pathology of Columbia University, George 
Crocker Special Research Fund, New York.] 
It is generally accepted that metastasis in malignant tumors 
is formed by the proliferation of tumor cells which have been 
transported to distant parts of the organism through the blood or 
lymph channels. The cells of the primary tumor penetrate in some 
manner into the lumen of the vessels, are swept away by currents 
as emboli, and finding lodgment in some distant part of the 
organism, they proliferate and form secondary tumors. 
This conception of the formation of metastasis was established 
through observation of autopsy material and no direct experi- 
mental proof of the matter was adduced up to the present. All 
experiments with intravascular injection of human tumor material 
into animals either gave negative results or were entirely 
untrustworthy. 
In all the extensive literature of the last decade on the subject 
of the transplantable cancer of the white mouse and rat there 
appears no statement in regard to intravascular injection of tumor 
material with the aim of forming metastasis. The only exception 
is a short note by Graf, who obtained negative results. 
Metastasis in malignant tumors of the white mouse and rat 
occurs rarely as compared with human cancer, and the channels 
for the transportation of the tumor cells are in a majority of cases 
the blood vessels. The reason for the rare occurrence of meta- 
stasis in the rat and mouse Ehrlich, in accordance with his athrep- 
tic theory of immunity, sees in the fact that tumors in these 
animals are usually of extreme malignancy and grow to very large 
