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 
pitrefying material (Turco). They withstand an ex- 
posure of one hour to 8U° 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 actei 
upon for three hours by bichloride of mercury (1 : 1000) 
they are killed, and in thirty minutes when 0.5 per cent. 
HCl is added to the solution. If the solution contains 
1: 1000 bichloride, with 5 per cent. carbolic and a 0.5 
per cent. HCl, 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- 
