136 AIDS TO BACTERIOLOGY 



Pathogenic Tetracocci. 



Micrococcus tetragenus occurs in phthisical cavities, 

 and sometimes in the pus of acute and chronic abscesses. 

 The organism occurs in pairs or fours, often seen sur- 

 rounded with an ill-defined capsule. It is Gram -positive, 

 slowly develops on gelatin as a thick white growth without 

 liquefaction, and on injection into white mice produces 

 general septicaemia. 



Micrococcus catarrhalis is present in pairs or tetrads 

 (often within the polymorphonuclear leucocytes) in the 

 discharges of the ' influenza cold ' and other forms of 

 nasal catarrh and bronchitis. It is sometimes concerned in 

 producing pyorrhoea and other buccal abscesses. It 

 grows at 22 C. It is Gram-negative, and produces 

 opaque colonies of so tough consistence on serum agar 

 that they often come away intact on a platinum 

 loop. 



Sarcina ventriculi occurs in the stomach, particularly 

 in cases of dilated stomach. 



Bacillus Pyocyaneus. 



The B. pyocyaneus is a small bacillus found in blue 

 and green pus, very actively motile, non-sporing, giving a 

 creamy growth on agar, to which it imparts a greenish 

 fluorescence and rapidly liquefying gelatin, the fluid being 

 similarly coloured. It may not produce blue pigment 

 for some days, and perhaps not at all until it has been 

 passed through animals (Lartigau). It does not stain 

 by Gram. The pigment can be extracted with chloro- 

 form, and consists of two pigmented bodies pyocyanin 

 and pyoxanthose. The organism occurs in various condi- 

 tions, accompanied by debility, wasting, and diarrhoea 

 the so-called marasmus and occasionally its presence 

 in water has caused dysentery. It has also been re- 

 sponsible for septicaemia. There are probably several 

 varieties of the organism, varying in virulence and pig- 

 ment production, of which the B. fluorescens liquefaciens, 

 an organism common in water, may be one. A body of 

 the nature of a ferment, ' pyocyanase,' when extracted 

 from cultures, is used for the prophylaxis and cure of 

 anthrax and diphtheria. 



