CHAP. VI.] PUS. 245 



SEC. 4. COLOURING MATTERS FOUND IN Pus. 



Pus is sometimes coloured with bilirubin. At other times it 

 presents a brownish colouration very similar to that due to bilirubiu, 

 but without giving the reactions of this body. More rarely it has a 

 blue or green colour. 



Pyocyanin. 



It has long ago been known that the pus of old sores sometimes 

 presents a blue or green colouration, especially the former. 



Fordos 1 shewed that under these circumstances a blue colouring 

 matter is formed to which he gave the definite name of pyocyanin. 



Mode of The material employed by Fordos consisted of 



preparation bandages stained with blue pus. These are steeped in 

 of Pyocyanin. a we ak solution of ammonia, which dissolves the colouring 

 matter and acquires a blueish or greenish tint. The ammoniacal 

 solution is shaken with chloroform, which dissolves pyocyanin, fat, 

 and a yellow colouring matter. 



The chloroformic solution is shaken with water holding a little 

 sulphuric acid in solution, when the colouring matter assumes a red 

 instead of a blue or blueish-green colour, and, leaving the chloroform, 

 is dissolved by the acid solution. The supernatant red liquid is then 

 separated, mixed with chloroform, and a little solution of caustic 

 baryta added, which causes the red colouring matter to become blue 

 again and to be taken up by the chloroform. On now evaporating 

 this liquid, pyocyanin is obtained, in the form of blue needles or of 

 rectangular plates. These are soluble in water, alcohol, and chloroform. 

 Pyocyanin possesses, as will have been gathered by the reader from 

 the above description of the mode of preparation, some of the pro- 

 perties of a blue vegetable colouring matter. 



Properties Pyocyanin is soluble in water, alcohol, chloroform, 



of Pyocyanin. and ether. It is decolourized by chlorine, concentrated 

 nitric acid, and ozone : it is blue in the presence of alkalies, red 

 in that of acids. When blue pus is kept from contact with air the 

 colour disappears, to reappear again when the liquid is shaken with air. 

 Pyocyanin has not hitherto been analysed. 



Pyocyanin a It has long been known that by being placed in 



vegetable proximity to a wound of which the purulent discharges 



are blue, suppurating surfaces which produced yellow pus 



are apt to furnish a liquid which is also blue or green. 



Liicke 2 thought he had discovered that the blue colour is due to a blue 



vibrio developing in the pus. The more recent investigations of Fitz 3 



1 Fordos, " Recherches sur la matiere colorante des suppurations bleues : Pyocyanin." 

 Paris, Comptes Rendus, LI., 1860, p. 215. 



2 Liicke, "Die sogenannte blaue Eiterung u. ihre Ursachen." ArcMv f. KliniscTie 

 Chirurgie, in., 1862, p. 135. 



3 Fitz, see an abstract entitled 'Recent Researches on Bacteria,' Quarterly Journal 

 of Microscopic Science, Jan. 1880, p. 106, from which the above account of Fitz's 

 researches is taken almost verbatim. 



