Given a noxious agent in a tissue, such, let us say, as a localized deposit of certain bacteria, the phagocytes swarm towards the locality where the bacteria have taken up their residence.
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).
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.
It has, however, been demonstrated that the senile whitening of human hair is due to the presence of phagocytes, which devour the pigment-bodies; and from microscopic observations recently made by the French naturalist Dr E.
The phagocytes are attracted from the blood vessels and elsewhere towards the noxious focus by the chemiotaxis exerted upon them by the toxins secreted by the bacteria contained within it.