Phagocytosis — Opsonins 113 



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

 the phagocytes are killed and dissolved — phagolysis. 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 en- 

 zyme of the macrophages, which Metchiiikoff calls macrocytase, 

 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 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 Metchnikoff, 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 Metchnikoff 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 

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

 ferent blood-serums possessed the power of killing bacteria in larger 

 numbers, but that the bactericidal power of the serum soon 

 disappeared, after which the serum became a good culture-medium 

 for the very bacteria it had formerly destroyed. Metchnikoff 

 objected to the observations, declaring that all the phenomena were 

 ultimately referable to the leukocytes, so Nuttall investigated 



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

 f'Proc. Royal Society of London," 1904, Lxxxn, p. 357. 

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

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

 Kriiger. 



Ir'Centralbl. f. Bakt.," etc., i^po, vii, p. 753. 

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

 ttlbid, Bd.iv, 3S3. 



