352 PROTECTIVE INOCULATIONS. 



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 

 developed 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 origi- 

 nal potency indefinitely ; in direct sunlight it is completely destroyed 

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

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

 chloric acid in the proportion of 0.55 per cent; terchloride of iodine 

 destroys it in the proportion of 0.5 per cent; cresol in one 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. 



Brieger (1886) first succeeded in obtaining from impure cultures 

 of the tetanus bacillus a crystallizable toxic substance, called by him 

 tetanin, which was found to kill small animals in very minute doses 

 and with the characteristic symptoms of tetanus. More recently Kit- 

 asato and Weyl have obtained the same substance, by following 

 Brieger's method, from a pure culture of this bacillus. From a bouil- 

 lon made from one and one-fourth kilogrammes of lean beef, with the 

 addition of twenty -five grammes of peptone, they obtained 1.7118 

 grammes of hydrochlorate of tetauin. This proved fatal to white mice 

 in six hours in the dose of 0.05 gramme, and a dose of 0.105 gramme 

 caused characteristic tetanic convulsions and death within an hour. 

 The bacteriologists last named also obtained from their cultures the 

 tetanotoxin of Brieger. Two mice were inoculated subcutaneous!}' 

 with 0.003 gramme of this substance; one died at the end of five 

 hours without the development of tetanic symptoms ; the other sur- 

 vived. In addition to these substances, indol, phenol, and buty- 

 ric acid were demonstrated to be present in cultures of the tetanus 

 bacillus. 



The more recent researches of Brieger and Frankel, and of Kita- 

 sato, show that the toxic ptomain discovered by Brieger in 1886 is 

 not the substance to which cultures of the tetanus bacillus owe their 



