1. A single intravenous injection into dogs of a sufficient number of freshly washed typhoid bacteria produces the symptoms and pathology that characterize anaphylaxis in these animals.

2. These effects are not produced by the coagulable protein-free filtrate from a fresh emulsion, while a similar filtrate from an emulsion digested with leucoprotease is very potent, the toxic portion of the bacterial bodies being changed from a coagulable to a non-coagulable state.

3. The symptoms and pathology described are not specific, since they can be produced by substances other than typhoid toxins.

4. Digestion with leucoprotease furnishes a method of liberating toxic substances from typhoid bacteria resembling the processes of nature more closely than the methods heretofore used.

5. The toxic substances thus liberated are not destroyed by a heat and acid precipitation of the coagulable proteins, and are of the nature of primary proteoses.

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