A further application of the facts of chemiotaxis and phagocytosis has been made by Metchnikoff to the case of Inflammation.
The work of Metchnikoff, dating from about 1884, has proved of high importance, his theory of phagocytosis (vide infra) having given a great stimulus to research, and having also contributed to important advances.
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.
It has, moreover, been noticed that even in cases where phagocytosis exists a greater or less extent of degeneration of the tissue may be observed before phagocytosis occurs.
Metchnikoff showed that in animals immune to a given organism phagocytosis is present, whereas in susceptible animals it is deficient or absent.
By opsonic action is meant the effect which a serum has on bacteria in making them more susceptible to phagocytosis by the white corpuscles of the blood.
In the light of all the facts, however, especially those contains an opsonin which leads to phagocytosis of the bacillus, and the latter is then destroyed by the leucocytes.
These matters, however, and others such as phagocytosis (first described by Metchnikoff in 1884), and the epoch-making discovery of the opsonins of the blood by Wright, do not here concern us (see II.