388 BACTERIOLOGY. 



that of a miniature pine-tree. Alkaline bouillon is ren- 

 dered somewhat turbid by the growth of the tetanus 

 bacillus. In all cases a production of gas results, accom- 

 panied by a characteristic and very disagreeable empy- 

 reumatic odor. It also grows in acid culture media, 

 but of itself produces no acid. It develops in milk 

 without coagulating it, and starch is not hydrated by 

 it in its growth (Sanfelice). 



The spores of the tetanus bacillus are very resistant 

 to outside influences; they retain their vitality for 

 months and years in a desiccated condition, and are 

 not destroyed in two and a half months when present in 

 putrefying material (Turco). They withstand an ex- 

 posure of one hour to 80 C., but are killed by an ex- 

 posure of five minutes to 100 C. in the steam sterilizer. 

 They resist the action of 5 per cent, carbolic acid for 

 ten hours, but succumb when exposed to it for fifteen 

 hours. A 5 per cent, solution of carbolic acid, how- 

 ever, to which 0.5 per cent, of hydrochloric acid has 

 been added, destroys them in two hours. When acted 

 upon for three hours by bichloride of mercury (1 : 1000) 

 they are killed, and in thirty minutes when 0.5 per cent. 

 HC1 is added to the solution. If the solution contains 

 1 : 1000 bichloride, with 5 per cent, carbolic and a 0.5 

 per cent. HC1, the spores are killed in ten minutes. 

 Silver nitrate solutions destroy the spores in one minute 

 in 1 per cent, solution and in five minutes in 1 : 1000 

 solution. 



Pathogenesis. In mice, guinea-pigs, rabbits, rats, 

 horses, goats, and a number of other animals inocula- 

 tions of pure cultures of the tetanus bacillus cause typi- 

 cal .tetanus after an incubation of from one to three 

 days. A mere trace only as much as remains cling- 



