1 98 BACTERIOLOGY. 



develops, and on potatoes the cocci form a layer 

 which is similarly coloured. 



Staphylococcus cereus flavus.* Cocci which 

 also occur in pus. If cultivated in nutrient jelly the 

 growth, which is at first white, becomes a lemon- 

 yellow, somewhat darker in colour than Staphylococcus 

 pyo genes citreus. Microscopically Staphylococcus cereus 

 flavus corresponds with Staphylococcus cereus albus, 

 and they both form zooglcea of medium-sized cocci 

 (diam. i'i6/i). Inoculation experiments with both 

 kinds give negative results. Among the micro- 

 organisms present in pus a coccus has been de- 

 scribed as occurring occasionally, which is almost 

 identical with Bacterium pneumonia crouposce ; com- 

 pare also Streptococcus pyogenes (p. 114) and Micro- 

 coccus pyo genes aureus (p. 122). 



Bacillus pyogenes foetidus.f Small rods, 

 with rounded ends of about 1*45 /A in length, 

 and '58 [A in width ; often in twos, or chains. 

 When cultivated in nutrient gelatine, a greyish, 

 veil-like growth forms on the surface. In plate 

 cultivations white points appear after twenty-four 

 hours, which develop into greyish spots, and these 

 enlarging coalesce into a layer. In nutrient agar- 

 agar the cultivation resembles the growth on 

 gelatine. On blood serum a moderately thick, 

 greyish-white streak develops, and on sterilised 

 potato an abundant, shining, brownish culture. 

 From all these media a putrid odour emanates, but 



* Passet, ibid. t Passet, ibid. 



