Vital Resistance Pathogenesis 607 



Milk. In milk the growth is rapid and luxuriant under 

 anaerobic conditions, but does not take place in cultures 

 exposed to the air. The milk is coagulated in from twenty- 

 four to forty-eight hours, the coagulum being either uniform 

 or firm, retracted, and furrowed by gas bubbles. When 

 litmus has been added to the milk, it becomes decolorized 

 when the culture is kept without oxygen, but turns pink 

 when it is exposed to the air. 



Potato. The bacillus will also grow upon potato when the 

 tubes are inclosed in an anaerobic apparatus. There is a 

 copious gas-development in the fluid at the bottom and sides 

 of the tube, so that the potato becomes surrounded by a 

 froth. After complete absorption of the oxygen a thin, 

 moist, grayish-white growth takes place upon the surface of 

 the medium. 



Vital Resistance. 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 

 died in three days, while in the absorption experiments it 

 was kept alive at the body temperature for one hundred and 

 twenty-three days. It is said to live longer in plain agar 

 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. 



Pathogenesis. The pathogenic powers of the bacillus are 

 limited, and while in some infected cases it seems to be the 

 cause of death, its power to do mischief in the body seems to 

 depend entirely upon the pre-existence of depressing and 

 devitalizing conditions predisposing to its growth. 



Being anaerobic, the bacilli are unable to live in the cir- 

 culating blood, though they grow in old clots and in cavities, 

 such as the uterus, etc., where little oxygen enters, and from 

 which they enter the blood and are distributed. 



In support of these views Welch and Nuttall show that 

 when a healthy rabbit is injected with 2.5 c.c. of a fresh 

 sugar-bouillon into the ear-vein, it usually recovers without 

 any evident symptoms. After similar injection with but i 

 c.c. of the culture, a pregnant rabbit carrying two dead 

 embryos, died in twenty-one hours. It seems that the 

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



