When tetanus toxin is injected into laboratory animals, such as the cat, guinea-pig or rat, the muscles near the site of the injection are the first affected; and if the dose is not too great, the tetanic contractions may remain entirely confined to the limb which receives the toxin. Cats are resistant and develop general tetanus less readily than the rat or guinea-pig and are for this reason especially suited for the study of local tetanus. Doses up to 1 cc. per kilogram of body weight produce only a local effect in the cat, although 0.004 cc. per kilogram of the same toxin will produce a generalized tetanus in the guinea-pig. For this reason, it is much easier to obtain advanced stages of tetanus contracture in the cat. It is well known that tetanus toxin acts on the central nervous system because section of the motor nerve prevents the development