78 Manual of Veterinary Microbiology. 



to the limitation of, or recovery from, the disease, by 

 opposing itself to the multiplication, and interfering 

 with the nutrition of the introduced germs ; the 

 phagocytes then assume the duty of freeing the or- 

 ganism from these enfeebled germs. 



Elimination of microbes. — The infected organism 

 may free itself from microbes by the local reaction 

 which their presence excites. The germs of pus, for 

 example, determine around them the diapedesis of 

 leucocytes and these destroy by phagocytosis a large 

 number of germs. On the other hand, at the same 

 time that the accumulation of leucocytes within the 

 meshes of the vascular network presents a certain 

 degree of obstruction to the nutrition of the mi- 

 crobes, the microbic secretions act upon the leuco- 

 cytes, either by virtue of their dissolving disastases or 

 of their toxic products, so that a parallel destruction 

 ensues of white corpuscles and of microbes. Whilst 

 this double destruction goes on at the center of the 

 focus, the surviving germs continue to invade the 

 peripheral tissues until there is formed all around the 

 invading army a sufficient barrier of phagocytes. 

 We then see the limitation of the abscess, and, occa- 

 sionally, its encystment by fibrous organization of 

 the limiting tissues ; but more frequently the exten- 

 sion of the pyogenic inflammation gives rise to soften- 

 ing, perforation of the integument, and the elimina- 

 tion of the pus and therefore of the germs, the cause 

 of all the trouble. 



The natural elimination of pathogenic microbes can 

 occur in all cases in which the lesions they deter- 

 mine are situated near the surface of the skin or 

 mucous membranes communicating directly with the 



