59° PATHOGENIC BACTERIA. 



thin, moist, grayish-white growth takes place upon the 

 surface of the potato. 



The vital resistance of the organism is not great. Its 

 thermal death-point was found to be 58 C. after ten 

 minutes' exposure. Cultures made by displacing the air 

 with hydrogen are less vigorous than those in which the 

 oxygen is absorbed from the air by pyrogallic acid. It 

 was found that in the former class of cultures the bacillus 

 generally died in three days, while in the absorption ex- 

 periments it was kept alive at the body-temperature for 

 one hundred and twenty-three days. It is said to live 

 longer in plain than in sugar-agar. To keep the cultures 

 alive it has been recommended to seal the agar-agar tube 

 after two or three days' growth. 



It is believed that the natural habitat of the bacterium 

 is the soil, but there is reason to think that it occurs in 

 the intestine at times, and it may occasionally be found 

 upon the skin. 



The pathogenic powers of the bacillus are limited, and 

 while in some cases it seems to be the cause of a fatal 

 outcome in infected cases, its power to do mischief in the 

 body seems to depend upon the pre-existence of other 

 depressing and devitalizing conditions predisposing to its 

 growth. 



Being anaerobic, the bacilli are unable to live in the 

 circulating blood, but they grow in old clots and in cav- 

 ities, such as the uterus, etc., where but little oxygen 

 ever enters, and from such areas enter the blood and are 

 distributed. 



In support of these views Welch and Nuttall cite the 

 result of inoculation into healthy and diseased rabbits. 

 When a healthy rabbit is injected with 2^ c.cm. of a 

 fresh sugar-bouillon into the ear-vein it generally recov- 

 ers without any evident symptoms. One of their rabbits 

 was pregnant, and at time of injection was carrying two 

 dead embryos. After similar injection with but 1 c.cm. 

 of the culture it died in twenty-one hours. It seems that 

 the bacilli were first able to secure a foothold in the dead 



