Phagocytosis — Opsonins 107 



that the enclosure of bacteria within the cells sometimes results in 

 the death of the cells, sometimes in the death of the bacteria; that 

 phagocytosis is much more active in diseases in which the bacteria 

 have limited toxicogenic powers, and in which they probably exert 

 a positively chemotactic influence upon the cells, than in cases in 

 which the bacteria are strongly toxicogenic and probably exert an 

 injurious and negatively chemotactic influence upon them, and 

 that when the toxicogenic power of the bacteria is great, many of 

 the phagocytes are killed and dissolved — pkagolysis. Study of 

 the primitive forms of animal life shows that amebae constantly 

 feed upon smaller organisms, some almost exclusively upon bacteria, 

 which they are able to kill and digest through an intracellular 

 enzyme demonstrated by Mouton,* and called amebadiastase, and 

 regarded as a form of trypsin. The intracellular digestion of 

 ccelenterate animals is accomplished by means of actinodiastase, an 

 enzyme discovered by Fredericq, and studied by Mesnil. It seems 

 to be related to papine and digests albuminoids. The digestion of 

 erythrocytes and tissue fragments is accomplished through an 

 enzyme of the macrophages, which Metschnikoff calls macrocytase, 

 that of bacteria through an enzyme of the microphages, which he 

 caUs microcytase. In phagolysis these respective ferments are 

 liberated into the plasma, imparting to it a bactericidal and bacterio- 

 lytic action similar to that normally peculiar to the cytoplasm of the 

 cells. The dissemination of the enzymes in phagolysis, with re- 

 sulting bacteriolytic power of the blood plasma and serum, is a 

 later modification of the original conception of Metschnikoff, that 

 the invading parasites were eaten up by the phagocytes, and was 

 made necessary by the investigation of the bactericidal property of 

 the body juices. The experiments of Wright and Douglas f indi- 

 cate that the action of the phagocytes upon the bacteria is not 

 immediate, but only subsequent to a preparative action upon the 

 organisms by substances contained in serum, to which they have 

 given the name "Opsonins" (Lat. opsono, "I prepare a meal for")- 

 Long before Metschnikofi began his studies of the phagocytes 

 Traube and GscheidelJ observed that the blood-plasma possessed 

 the power of destroying the vitality of bacteria. Grohman§ next 

 observed that not only the intravascular, but also the extravascular 

 blood possessed this property. Further studies of the subject were 

 made by von Fodor.|| The systematic investigation of the bac- 

 tericidal activity of blood-serum in vitro was next taken up by 

 Fliigge,** and more particularly by Nuttall,tt who found that dif- 



* " Compte rendu de I'Acad. des Sciences de Paris," 1901, cxxxiii, p. 244. 



t "Proc. Royal Society of London," 1904, Lxxxii, p. 357. 



X " Jahresberichte der schles. Ges. f. vaterl. Kultur," 1874. 



§ " Untersuchungen aus dem physiol. Institut zu Dorpat," Dorpat, 1884; 

 Kriiger. 



|l " Centralbl. f. Bakt.," etc., 1890, vii, p. 753. 

 ** "Zeilschrift fur Hygiene," Bd. iv, S. 208. 

 tt Ibid., Bd. IV, 353. 



