SYSTEMATIC AND DESCRIPTIVE. 12^ 



any gas develop. Albumen is converted by their 

 action into peptones. 



They occur in the pus of boils and in the abscesses 

 of pyaemia, puerperal fever, and acute osteomyelitis. 

 Injected into the peritoneal cavity of animals, they 

 set up peritonitis, and introduced into the jugular 

 vein they produce septicaemia and death. When a 

 small quantity of a cultivation was introduced into 

 the jugular vein after previous fracture or contusion 

 of the bones of the leg, the animal died in about 

 ten days, and abscesses were found in and around 

 the bones, and in some cases in the lungs and 

 kidneys. Similar cocci were found in the blood 

 and pus of the animals.* 



Micrococcus pyocyaneus, Gessard. Cocci 

 ellipsoidal. Cultivated in sterilised nourishing 

 solution, they colour it blue, especially on the sur- 

 face. The deeper part of the medium becomes 

 decolorised again by the action of the micro- 

 organism, but when shaken with air develops the 

 colour. The pigment formed by the cocci is a de- 

 finite principle, pyocyanin.f It can be extracted 

 with chloroform from the pus and .washings of 

 bandages ; it is soluble in acidulated water, which 

 it colours red. In neutral solution it becomes blue. 

 It crystallises in chloroform in long needles, and 

 forms sometimes lamellae and prisms. 



* Becker, Deutsche Med. Wochenschr,, Nov. 1883. 

 t Gessard, De la pyocyanine et de son microbe. Paris these. 

 1882. 



