318 i:.\< Ti:ilIOLOGY. 



attributed to individual peculiarities of different species 

 of bacteria that were under examination, an opinion 

 that is borne out by more recent studies, from which it 

 has been decided that the genuine plague or pest bacillus 

 does not stain by Gram's method. 



It may be cultivated upon ordinary nutrient media, 



Bacillus of bubonic plague: A, in pus from suppurating bubo; B, the 

 bacillus very much enlarged to show peculiar polar staining. 



although preference is given by some to a neutral or 

 slightly alkaline 2 per cent, peptone solution containing 

 from 1 to 2 per cent, of gelatin. 



The most favorable temperature for its growth is 

 between 36 and 39 C. Its colonies on glycerin-agar- 

 agar and on coagulated blood-serum are described as 



