324 INFECTION AND RESISTANCE 



upon the cooperation of two such bodies. It is likely, therefore, that 

 the mechanism of normal and of immune opsonic action may, after 

 all, differ only in quantitative relations between the two. 



For assuming this to be an antibody-alexin mechanism like hemol- 

 ysis, we may recall the work of Morgenroth and Sachs on the rela- 

 tions between amboceptor and complement in hemolysis. There we 

 saw that a large amount of amboceptor would cause hemolysis in the 

 presence of a small amount of complement and vice versa. There- 

 fore, here, too, in normal serum the small quantity of amboceptor or 

 specific thermostable opsonin (bacteriotropin) may act very power- 

 fully in the presence of the alexin. When the latter is destroyed, 

 however, the minute quantity of specific thermostable opsonin is 

 hardly enough to do more than initiate slight phagocytosis of com- 

 paratively non-resistant bacteria, whereas the large amount of spe- 

 cific sensitizer left in immune sera after inactivation may still lead 

 to strong bacteriotropic action. In outlining this explanation we 

 have consistently drawn upon the analogy between thermostable op- 

 sonin and amboceptor or sensitizer. Whether or not these two sub- 

 stances are identical is by no means positively determined and must 

 be considered an open question for the present. However, from the 

 above, it seems to us that much testifies in favor of such an identi- 

 fication. 55 



The preceding discussions have ignored the possibility that apart 

 from opsonic or bacteriotropic action on the bacteria there may be 

 a difference in phagocytic energy which depends upon inherent prop- 

 erties of the leukocyte itself. 



Indeed, the technique by which the researches of Wright and 

 his followers were carried out does not in any way take into account 

 the source of the leukocytes as a possible variable factor. There is, 

 however, a considerable amount of evidence which points to differ- 

 ences in phagocytic powers residing in the leukocytes themselves 

 independent of the serum. Park and Biggs 5G have demonstrated 

 such differences for the leukocytes of normal persons in the phagocy- 

 tosis of staphylococci, and more extensive researches have been made 

 with similar results, in the case both of staphylococci and tubercle 

 bacilli by Glynn and Cox. 57 



The last-named authors, moreover, recognized the necessity, in 

 making such investigations, of experimenting with leukocyte emul- 

 sions containing approximately the same number of cells, for, as 

 Fleming 58 had shown, if unequal leukocytic emulsions are used, 



55 Pfeiffer (quoted from P. Th. Miiller) regards opsonic action as due 

 to a combined action of amboceptor and complement and speaks of it as an 

 "Andauung" of the bacteria for the leukocyte which we may translate best 

 as a partial predigestion. 



56 Park and Biggs. Jour. Med. Res., Vol. 17, 1907. 



57 Glynn and Cox. Jour. Path, and Bact., 14, 1910. 



58 Fleming. Practitioner, London, Vol. 80, 1908. 



