BACILLUS PYOCYANEUS. 355 



Bacillus nibcr (Frank). 



These are actively moving rods, occurring singly or 

 united in twos or fours ; in some of these rods there are 

 two to four highly refracting granules (spores). The 

 organisms produce, when grown on boiled rice, a red 

 colour resembling that of red lead or sealing-wax. 

 Nothing further is as yet known regarding this organ- 

 ism. 



Bacillus pyocyaneus. 

 (Bacterium aeruginosum, Organism of greenish-blue pun.) 



It has been known for a long time that the greenish- 

 blue colour which sometimes appears in the dressings 

 on suppurating wounds is occasioned by micro-organisms. 

 More or less pure cultivations have also been made by 

 numerous investigators, and most recently by Gessard 

 and Charrin ; but nevertheless the majority of observers 

 do not seem to have obtained the organism quite pure, 

 for they have described it usually 

 as a round or oval micrococcus. 

 The organism can be readily 

 isolated by the aid of gelatine $x y & 



plates. It is a thin fine bacillus, Fig. 95. Baoim f f Morphological 

 of varying length, the average ^emah-blue P u characters, 

 length being about the same as 



that of bacillus murisepticus, the thickness somewhat 

 greater. Chains of two or three bacilli are observed, 

 but usually they form irregular masses, united together 

 by a tenacious zoogla3a ; spore-bearing bacilli are also 

 not uncommon, and in that case they are usually some- 

 what thickened. On gelatine plates the colonies form, Cultivations. 

 after 24 hours, whitish opaque patches, which under a 

 low power show a round, but not sharp outline, of a 

 yellowish colour, and with radiating markings ; the whole 

 of the gelatine presents a greenish shiny appearance. 

 Twenty-four hours later the deep colonies have a grey 

 centre, with a dark brownish-yellow zone at the outer- 

 most border, from which delicate radially arranged threads 



