PATHOGENIC ANAEROBIC BACILLI. 535 



are killed in the same way by somewhat larger quantities 0.3 to 0.5 

 cubic centimetre (Kitasato). Pigeons are very slightly susceptible. 

 The tetanic symptoms are first developed in the vicinity of the point 

 of inoculation ; if the animal is inoculated in the posterior portion of 

 the body the hind legs first show tetanic contraction, if in the fore 

 part of the body the muscles of the neck are first affected. At the 

 autopsy there is a certain amount of hyperaemia at the point of in- 

 oculation, but no pus is formed ; in inoculations with garden earth, 

 or accidental inoculations in man, pus is commonly found in the 

 vicinity of the inoculation wound. The various organs are normal 

 in appearance. Kitasato says that he has not been able to demon- 

 strate the presence of the bacillus or of spores in the spinal marrow, 

 the nerves, muscles, spleen, liver, lungs, kidneys, or blood from the 

 heart ; nor has he been able to obtain cultures from the various 

 organs. In mice which were inoculated at the root of the tail 

 Kitasato was able to demonstrate the presence of the bacilli at 

 the point of inoculation by the microscopical examination of an 

 excised piece of the tissues for eight to ten hours after the inocula- 

 tion ; later than this they were not found. In pus from the inocu- 

 lation wounds of men and animals accidentally infected the bacilli 

 are present, but the formation of spores does not always oc- 

 cur. According to Kitasato, the sooner death has occurred after 

 accidental inoculation the less likely are spores to be found in the 

 rods, but from pus in which no spores are seen cultures of the 

 bacillus may be obtained in which spores will develop in the usual 

 manner. 



Guinea-pigs are even more susceptible to the tetanus poison than 

 mice, and rabbits less so. The amount of filtrate from a slightly 

 alkaline bouillon culture required to kill a mouse is extremely minute 

 0.00001 cubic centimetre (Kitasato). The tetanic symptoms are de- 

 veloped within three days ; if the animal is not affected within four 

 days it escapes entirely. The tetanus poison is destroyed by a tem- 

 perature of 65 C. maintained for five minutes, or 60 for twenty 

 minutes, or 55 for an hour and a half ; in the incubating oven at 

 37 C. it gradually loses its toxic potency ; in diffuse daylight, also, 

 its toxic power is gradually lost ; in a cool, dark place it retains its 

 original potency indefinitely ; in direct sunlight it is completely de- 

 stroyed in from fifteen to eighteen hours ; it is not injured by being 

 largely diluted with distilled water ; it is destroyed in an hour by 

 hydrochloric acid in the proportion of 0.55 per cent ; terchloride of 

 iodine destroys it in the proportion of 0. 5 per cent, cresol in 1 per 

 cent one hour's exposure. In general it is destroyed by acids and 

 by alkalies. Blood serum from cattle, horses, sheep, rabbits, rats, or 

 guinea-pigs does not modify its toxic properties. 



