THE BAOILLVS OF MALIGNANT (EDEMA. 525 



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 inter- 

 lacing 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 devcloj^ment 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. 96, a) and contains gas-bubbles. Of the internal 

 organs only the spleen shows much change. It is large, 

 dark in color, and contains numerous bacilli. If the 

 autopsy be made immediately after death, bacilli are 

 rarely found in the blood of the heart; but if de- 

 ferred for several hours, the organisms will be found 

 in this locality also, a fact that speaks for their Tuulti- 



