338 INFECTION AND IMMUNITY 



merely upon an increase of the normal opsonins or whether the 

 newly formed immune opsonins were entirely different substances. 

 The greater thermostability of the opsonins in immune sera seemed, 

 at first, to support the latter view. Dean, 11 however, showed that 

 not all of the normal opsonins are thermolabile and that, by absorp- 

 tion experiments, bacteria treated with normal sera could be pre- 

 vented from taking up opsonins from immune sera. These facts 

 seem to point strongly toward the identity of normal and immune 

 opsonic substances. 



Further study of the opsonins has led to numerous other ques- 

 tions regarding their structure, their relation to other immune 

 bodies, etc., which are largely still in the stage of controversy, and 

 for which the original monographs must be consulted. 



The controversial questions may be briefly reviewed as follows: 



As stated above, Wright believed originally that the bodies dis- 

 covered by him in normal sera, the "normal opsonins," in other 

 words, were distinct bodies that could not be identified with either 

 the complement or antibodies present in serum. Neuf eld and Hiine, 12 

 Levaditi and Inmann, 13 and others, on the other hand, maintain 

 that the opsonic action of normal serum, at least, is intimately 

 related to the complement contents of such serum. 



They base this contention not only upon the thermolability of 

 normal opsonins, but also upon the fact that opsonin may be removed 

 from normal serum at the same time as complement by the method 

 of complement fixation, detailed in another section (see pp. 295 

 and 315 ). 14 



The contention of Wright that the thermostable opsonic sub- 

 stances of immune serum are distinct bodies, not identical with the 

 amboceptors, is supported by the work of Hektoen, 15 Neufeld and 

 Topfer, 16 and others. The problem, however, can by no means be 

 regarded as finally settled, since other workers, notably Levaditi, 

 are inclined to identify the immune opsonins with lytic amboceptors. 



As to the structure of the opsonic substances, moreover, differ- 



11 Dean, Proc. Eoy. Soc., London, Ixxvi, 1905. 



12 Neufeld and Hune, Arb. a. d. kais. Gesundheitsamt, xxv. 



13 Levaditi and Inmann, Compt. rend, de la soc. de biol., 62, 1907. 



14 Levaditi, Presse medicale, 70, 1907. 

 15 Helctoen, Jour, of Inf. Dis., iii, 1906. 



16 Neuf eld und Topfer, Cent. f. Bakt., xxxviii, 1905. 



