138 A MANUAL OF BACTERIOLOGY 



die with the characteristic symptoms of the disease. 

 If a culture of the microbe is kept for two or three 

 months its virulence is lessened ; and an attenuated 

 virus has been successfully used by Pasteur in the 

 protective inoculation of fowls against this disease. 

 This microbe is pathogenic in rabbits as well as 

 fowls, but guinea-pigs have an immunity; it is 

 aerobic, and is cultivated in contact with sterilised 

 air or in aerated fluids. In fact, ' its toxic effect has 

 been supposed to be due to the abstraction of 

 oxygen from the blood, producing asphyxia.' B. 

 cholerce gallinarum grows on gelatine as small, 

 round, white colonies with lemon-yellow centre. It 

 grows on potatoes at 37C., producing yellow-grey 

 drops. M. Duclaux 1 has shown that this microbe 

 produces a ptomaine; but when the ptomaine is 

 separated, by filtration through porous porcelain 

 from its microbe it does not produce fowl cholera ; 

 for it causes a passing sleep, which does not gener- 

 ally end fatally. From this fact the conclusion 

 may be drawn that in fowl cholera the microbe is 

 essentially the active agent in producing the disease. 

 Bacterium pseudo-pneumonicum. This microbe 

 forms greyish-white layers in test-tube cultivations ; 

 while on gelatine plates the colonies appear as white 

 dots. It grows on sterilised potatoes at 37 C., 

 giving rise to a white, viscid layer; it measures 

 1*16 fj, in length, and 0*8 p in breadth, and requires 

 air for its growth. It is only slightly pathogenic. 

 B. pseudo-pneumonicum occurs in pus taken from 

 abscesses. 



1 Ferments et Maladies. 



