1. Tuberculo-protein in solution induces the formation of monocytes in the normal animal and tubercles of epithelioid cells in that which is tuberculous.
2. Freshly precipitated tuberculo-proteins from the culture media and from the bacilli induce a moderate formation of epithelioid cells in normal animals, and more in the tuberculous.
3. Insoluble forms of tuberculo-protein induce complex tubercular tissue in normal animals. This action is enhanced in the tuberculous.