1. There seems no further possibility of questioning the opinion that the development of tuberculin sensitiveness is definitely associated with the development of tissue reactions in the form of inflammatory processes; the mere development of antibodies on the injection of dissolved bacterial materials does not induce allergy.
2. Passive transfer of tuberculin allergy to guinea pigs may be accomplished by injections not only of the tissue extracts of the tuberculous foci of rabbits, but also of the sera of such rabbits, provided multiple, well developed, and not too advanced lesions are present in the rabbits furnishing them. The exact criteria by which such results can be regularly obtained have not yet been ascertained; our results in this respect, though definite, have been irregular and occasional. It is clear, moreover, that the capacity to convey such allergic hypersensitiveness has no relationship to the precipitating capacity of the serum for residue materials.
3. Just as the allergy-conveying power of the serum and its precipitating powers for residue are separable, so, also, the bacterial extracts representing the antigens for these reactions are separable, the residue material being particularly concerned in the specific precipitations with immune serum, the so called nucleoprotein being associated with allergic reactions in the tuberculous animals.