THE BIOLOGY OF MICROBES, ETC. 123 



abscesses; generally, however, they begin to act 

 after inflammation has been previously induced. 

 This inflammation may be caused by an injury, by 

 the absorption of chemically irritating substances 

 from wounds, by colds, etc. 



(7.) There are several different kinds of micrococci 

 associated with suppuration. 



(8.) Micrococci cause suppuration by the produc- 

 tion of a chemically irritating substance (probably 

 a ptomaine), which, if applied to the tissues in a 

 concentrated form, causes necrosis of the tissue, 



Fio. 32. MICROBES IN PURPURA. 



(Watson Uheyne.) 



A, Micrococci. B, Bacilli. 



X 2500. 



but, if more dilute, causes inflammation and sup- 

 puration. 



Micrococcus in purpura hcemorrhagica. Watson 

 Cheyne 1 has observed cocci (measuring 1'15 /* in 

 diameter) in certain cases of purpura hsemorrhagica. 

 This microbe forms colonies in the blood ; and the 

 haemorrhages are due to the plugging of the small 

 vessels by masses of these microbes. The microbes 

 occur in chains (Fig. 32), and stain well with 



1 Transactions of the Pathdogkal Society of London, 1884. 



