Further investigations about the passive transfer of sensitivity caused by anti-thymocyte serum.

Soluble materials were obtained from the spleens and thymuses removed from mice sensitized by anti-thymocyte serum or normal horse serum. These materials were administered to mice. In the mice thus treated, anaphylaxis was provoked by iv inoculation of serum. Irreversible shock did not occur. Reversible anaphylactoid symptoms occured among the animals treated with the supernatants of cells of sensitized animals, in case when these cells have been disrupted by osmotic shock.