BACILLUS TETANI 475 



organisms grow well in a vacuum or in an atmosphere of hydrogen or 

 nitrogen; they grow poorly or not at all in an atmosphere of carbon 

 dioxide. Growth does not take place below 14 C. or above 45 C.; 

 the optimum is 37 C. Growth is slow at 20 C. and spore formation 

 proceeds sluggishly. At 37 C. growth and spore formation are opti- 

 mum. Growth is fairly rapid at 43 C., but spore formation is greatly 

 interfered with, and above 45 C. growth ceases. 



The spores are very resistant to drying; when kept in the dark and 

 cool they may survive for years. Henri jean 1 has found that tetanus 

 spores may remain viable and virulent for nearly eleven years. The 

 resistance of spores to heat is a subject on which there is great difference 

 of opinion. Theobald Smith 2 has studied the resistance of tetanus 

 spores under varying conditions, and his results are the most trust- 

 worthy available. In gelatin sporulation is relatively feeble and 

 spores formed in this medium do not appear to be very resistant. 

 He states that a majority of tetanus spores survive an exposure to 

 flowing steam for forty minutes, occasionally for sixty minutes; and 

 in one experiment a seventy-minute exposure did not destroy all 

 spores. Morax and Marie 3 have found that dried spores are killed 

 by an exposure to dry heat at 125 C. for twenty minutes. A 5 per 

 cent, solution of carbolic acid kills tetanus spores in about ten hours; 

 mercuric chloride in a dilution of 1 to 1000 kills them in three hours; 

 the addition of 0.5 per cent, hydrochloric acid increases the germicidal 

 action of both carbolic acid and mercuric chloride. A 1 per cent, 

 solution of silver nitrate kills tetanus spores in one minute, and a 

 0.1 per cent, solution in five minutes. lodoform is said to be par- 

 ticularly efficient. 



Products of Growth. Among the products of metabolism of the 

 tetanus bacillus in sugar-free media are indol, hydrogen sulphide, and 

 mercaptan, which impart an extremely disagreeable odor to cultures 

 of the organism. Bacillus tetani ferments dextrose and maltose, pro- 

 ducing acid, partly lactic, as well as considerable amounts of carbon 

 dioxide and hydrogen. Bioses other than maltose, and polysaccharides 

 are not fermented. 



The most characteristic and striking metabolic product, however, is 

 an extremely potent, soluble, extracellular toxin. This toxin, as Ehrlich 

 has shown, 4 contains at least two distinct components in varying 



1 Ann. de la Soc. m6d.-chir. de Li&ge, 1891, 367. 



2 Jour. Am. Med. Assn., 1908, 1, 929. 



3 Ann. Inst. Past., 1902, 421. 



4 Berl. klin. Wchnschr., 1898, No. 12. 



