Phagocytosis Opsonins 127 



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 Mesml. It seems to be related 

 to papine and digests albuminoids. The digestion of ery- 

 throcytes and tissue fragments is accomplished through an 

 enzyme of the macrophages, which Metschnikoff calls macro- 

 cytase, that of bacteria through an enzyme of the microphages, 

 which he calls microcytase. In phagolysis these respective 

 ferments are liberated into the plasma, imparting to it a 

 bactericidal and bacteriolytic action similar to that normally 

 peculiar to the cytoplasm of the cells. The dissemination 

 of the enzymes in phagolysis, with resulting 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 Douglasf 

 indicate 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 Metschnikoff began his studies of the pha- 

 gocytes Traube and Gscheidel I 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 extra vascular blood possessed 

 this property. The first exact investigations of the subject 

 were made by von Fodor. || The systematic investigation of 

 the bactericidal activity of blood-serum in vitro was next 

 taken up by Fliigge,** and more particularly by Nuttall,ft 

 who found that different blood-serums possessed the power 



* "Compte rendu de 1'Acad. des Sciences de Paris," 1901, cxxxm, 

 p. 244. 



< t " Proc. Royal Society of London," utxxii, p. 357, 1904- 

 t " Jahresberichte der Schles. Ges. f. vaterl. Kultur," 1874. 

 " Untersuchungen aus dem physiol. Institut zu Dorpat," Dorpat, 

 1884; Kriiger. 



|| "Centralbl. f. Bakt.," etc., 1890, vn, p. 753- 

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

 ft Ibid., Bd. IV, S. 353- 



