Chapter VII

THE MECHANISM OF NATURAL IMMUNITY AGAINST MICRO-ORGANISMS 175
The destruction of micro-organisms in natural immunity is an act
of resorption.—Part played by inflammation in natural
immunity.—Importance of microphages in immunity against
micro-organisms.—Chemiotaxis of leucocytes and ingestion of
micro-organisms.—Phagocytes are capable of ingesting living and
virulent micro-organisms.—The digestion of micro-organisms in
phagocytes is most often effected in a feebly acid
medium.—Bactericidal property of serums.—Phagocytic origin of
the bactericidal substance.—Theory of the secretion of the
bactericidal substance by leucocytes.—Comparison of the
bactericidal power of serums and of blood plasmas.—The
bactericidal substance of blood serums must not be considered a
secretion-product of leucocytes; it remains within the
phagocytes, so long as they are intact.—The cytases.—Two kinds
of cytases: macrocytase and microcytase.—Cytases are
endo-enzymes, allied to trypsins.—Changes in the staining
properties and in the form of micro-organisms in the
phagocytes.—Absence or rarity of fixatives in the serums of
animals endowed with natural immunity.—The agglutination of
micro-organisms does not play any important part in the
mechanism of natural immunity.—Absence of antitoxic property of
the body fluids in natural immunity.—The phagocytes destroy the
micro-organisms without their ingestion being preceded by
neutralisation of the toxins.