Phagocytes act as scavengers in ridding the body of noxious particles, and more especially of harmful bacteria.
The vanguard of this advancing army is composed of a more or less compact layer of the mono-nuclear phagocytes (polyblasts) accompanied by numerous new vessels.
This is accomplished by a twofold agency, for while numbers of them are seized upon by the granulation phagocytes, others are broken up and dissolved by the liquid filling the granulation interspaces (Afanassieff).
Then as regards natural powers of destroying bacteria, phagocytosis aided by chemiotaxis plays a part, and it can be understood that an animal whose phagocytes are attracted by a particular bacterium will have an advantage over one in which this action is absent.
He also showed that the development of artificial immunity is attended by the appearance of phagocytosis; also, when an anti-serum is injected into an animal, the phagocytes which formerly were indifferent might move towards and destroy the bacteria.