444 -S^ GTERIOL OGY. 



stripes, easily to be detected with the aid of a small 

 hand-lens. In deep stab-cultures in agar-agar and gel- 

 atin development occurs only along the track of punc- 

 ture at a distance below the surface. Growth is fre- 

 quently accompanied by the production of gas-bubbles. 



It causes rapid liquefaction of blood-serum with 

 production of gas-bubbles, and in two or three days 

 the entire medium may have become converted into a 

 yellowish, semi-fluid mass. 



The most satisfactory results in the study of the col- 

 onies are obtained by the use of plates of nutrient agar- 

 agar kept in a chamber in which all oxygen has been 

 replaced by hydrogen. The colonies appear as dull 

 whitish points, irregular in outline, and when viewed 

 with a low-power lens are seen to be marked by a net- 

 work of branching and interlacing lines that radiate in 

 an irregular way from the centre toward the periphery. 



It grows well at the ordinary temperature of the 

 room, but reaches its highest development at the tem- 

 perature of the body. 



It stains readily with the ordinary aniline dyes. It 

 is decolorized when treated by Gram's method. 



Pathogenesis. The animals that are known to be 

 susceptible to inoculation with this organism are man, 

 horses, calves, dogs, goats, sheep, pigs, chickens, pig- 

 eons, rabbits, guinea-pigs, and mice. Cases are recorded 

 in which men and horses have developed the disease 

 after injuries, doubtless due to the introduction into the 

 wound, at the time, of soil or dust containing the or- 

 ganism. 



If one introduce into a pocket beneath the skin of a 

 susceptible animal about as much garden earth as can 

 be held upon the point of a penknife, the animal fre- 



