The application of an infusion of violet leaves was at one time believed to have the power of reducing the size of cancerous growths, but its use is now discredited.
From these experiments it is shown that cells taken from these growths and introduced into animals of the same species give rise to a cancerous growth, whose cells have acquired unlimited powers of proliferation.
Not only is this true of epithelial cells, but - the connective tissuecells of the supporting structure of cancerous growth, after repeated transplantation, may become so altered that a gradual evolution of apparently normal connective tissue into sarcomatous elements takes place, these giving rise to " mixed tumours."
- Secondary cancerous growth in heart wall.
The fact that it is possible to propagate these cells of one animal for years in other animals of the same species, without any loss of their vegetative vitality, suggests that this continued growth is kept up by a growth-stimulating substance present in the proper species of animal; this substance, however, has not the power of transforming the normal tissue into a cancerous one.