386 BACTERIOLOGT. 



entire medium may have become converted into a yel- 

 lowish, semi-fluid mass. 



The most satisfactory results in the study of the 

 colonies 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 been replaced by hydrogen.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 network 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, 

 pigeons, 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 organism. 



If one introduces 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- 

 quently dies in from twenty-four to forty-eight hours. 

 The most conspicuous result found at autopsy is a wide- 

 spread oedema at and about the seat of inoculation. The 

 oedematous fluid is at places clear, Avhile again it may be 

 marked with blood ; it is usually rich in bacilli (Fig. 

 83, a) and contains gas-bubbles. Of the internal 



