FACTORS DETERMINING PHAGOCYTOSIS 319 



tubercle bacilli, found that each of these organisms absorbed out 

 separately specific opsonins from normal serum, leaving those for 

 other bacteria but slightly reduced. Slight reduction of the opsonic 

 action for other micro-organisms might easily be explained by a 

 partial removal of complement which is bound to take place in such 

 experiments. Simon, Lamar and Bispham, 36 and some others failed 

 to find any such specificity. Russell, 37 Axamit and Tsuda, 38 and a 

 number of others obtained similar negative results in that a num- 

 ber of different bacteria seemed to absorb opsonins out of normal 

 serum indiscriminately and without specificity. On the other hand, 

 more recent careful work by Rosenow, 39 by Macdonald, 40 and by 

 Jtektoen 41 has upheld the original contention of Bulloch and West- 

 ern. The work of Rosenow, in which pneumococci were shown to 

 absorb out their specific opsonins from normal human serum, taking 

 out in part only those for streptococci, staphylococci, and tubercle 

 bacilli, is especially convincing, and the experiment of Hektoen with 

 normal hemopsonins (opsonins which cause the phagocytosis of red 

 blood cells) bear him out. 



It seems fair to conclude, therefore, that normal opsonins de- 

 pend upon the cooperation of a heat-stable and a heat-sensitive body. 

 The heat-stable body, analogous to normal sensitizer or amboceptor, is 

 specific and reactivable by the heat-sensitive body which appears to 

 be identical with alexin. This statement merely asserts the facts of 

 the dual mechanism of the process without assuming necessarily the 

 identity of the heat-stable body with sensitizer or that of the heat- 

 sensitive one with alexin, though this seems extremely probable. 



This question we will discuss again more particularly in connec- 

 tion with the bacteriotropins or immune opsonins. 



Further proof for such a complex constitution of the normal 

 opsonins has been adduced by means of absorption experiments at 

 C. by Cowie and Chapin. In our discussion of the lytic anti- 

 bodies we have seen that sensitizer or amboceptor may be absorbed 

 from serum by its specific antigen at C. but that the attachment 

 of alexin takes place only when the temperature is raised above this. 

 Practically no alexin is bound at the low temperature. Cowie and 

 Chapin, applying this method of investigation, showed : 



1. That normal human serum may have its opsonic power for 

 staphylococci removed by absorption with staphylococci at C. 



2. Serum so treated retains the power of reactivating the op- 

 sonin of heated normal serum. 



36 Simon, Lamar, and Bispham. Jour. Exp. Med., Vol. 8, 1906. 



37 Russell. Johns Hopk. Bull, Vol. 18, 1907. 



38 Axamit and Tsuda. Wien. klin. Woch., Vol. 20, No. 35, 1907. 



39 Rosenow. Jour. Inf. Dis., Vol. 4, 1907. 



40 Macdonald. Quoted from Hektoen, loc. cit.; Aberdeen Univ. Stu'dies, 

 Vol. 21, 1906, p. 323. 



41 Hektoen. Journ. Inf. Dis., Vol. 5, 1908. 



