1. Protein fractions derived from tubercle bacilli are toxic to the interior of Amœba dubia but have no action on the plasmalemma.
2. Phosphatide fractions dissolve the plasmalemma but have no effect on the internal cytoplasm.
3. The fatty acid fraction has a marked solvent action on the plasmalemma when brought in contact with the surface of the cell. When injected it may slowly penetrate the cytoplasm to dissolve the contiguous plasmalemma.
4. The polysaccharide fraction has no effect upon the surface membrane or upon the internal cytoplasm of Amœba dubia.