PHAGOCYTOSIS 193 



vent agent is of intracellular origin. Furthermore, he has shown that 

 the phagolysis can be prevented, and when this is done the peritoneal 

 fluid remains rich in leukocytes and phagocytic action is easily dem- 

 onstrated under the microscope. Still further, Levaditi has shown 

 that phagolysis may occur in other parts of the body. If the cholera 

 vibrio be injected into the circulation of a highly immunized guinea- 

 pig, the phagocytes practically disappear from the peripheral blood. 

 On sectioning the lungs they are found in clumps and evidently 

 injured. About them are seen masses of the vibrio undergoing diges- 

 tive changes. Positive chemotaxis still manifests its influence and 

 brings the phagocytes and bacilli together at the place where the 

 former, in undergoing dissolution, pour out a secretion which is fatal 

 to the latter. 



If cholera vibrios be injected into the anterior chamber of the eye 

 of a highly immunized guinea-pig, a place where there has been no 

 phagolysis, the phagocytes concentrate here and phagocytosis may be 

 demonstrated. 



Further elucidation of this subject seems unnecessary. It is evi- 

 dent that in acquired immunity there is increased activity and effec- 

 tiveness on the part of the phagocytes in the destruction of the invad- 

 ing organism, which may be destroyed by intracellular or extracellular 

 digestion. In either case the destructive agent is supplied by the 

 phagocytes. Metschnikoff holds that in the body intracellular digestion 

 is the rule and that extracellular destruction plays only a subordinate 

 role. 



Phagocytosis in Injuries and Disease. In this section we continue 

 to follow the teachings of Metschnikoff. In inflammation there is an 

 accumulation of phagocytes at the point of injury. When the injury 

 is aseptic, the functions of the phagocytes are to remove the injured 

 body cells and to repair the tissue. In septic wounds the additional 

 duty of destroying the foreign cells falls on the phagocytes. In the 

 lower animals which possess neither nerves nor blood vessels, the 

 motile connective-tissue cells devour the invading organisms. In the 

 higher animals the process is more complicated. Through nerve stim- 

 ulation, the blood vessels of the injured part are dilated, phagocytes 

 from distant parts of the body are brought to the locality and pass 



