BACILLUS (EDEMATIS. 547 



duction of gas-bubbles, and in two or three days the 

 entire medium may have become converted into a 

 yellowish, semifluid 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 been replaced by hydrogen.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 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 

 does not stain by Gram's method. 



PATHOGENESIS. The animals known to be suscepti- 

 ble to inoculation with this organism are man, horses, 

 calves, dogs, goats, sheep, pigs, chickens, pigeons, rab- 

 bits, 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 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- 

 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 site of inoculation. The 

 oedematous fluid is in some places clear, while at others it 

 may be stained with blood ; it is usually rich in bacilli 

 (Fig. 88, A) and contains gas-bubbles. Of the internal 



