OPSONIC ACTION 171 



of normal serum belong to the group of complements 

 (alexines). As shown above, we found a striking re- 

 semblance in the diminution of haemolytic, bactericidal and 

 opsonic action produced by the different methods of ab- 

 sorption, but at present we pronounce no opinion as to 

 the identity or non-identity of the substances producing 

 these effects. Much remains to be done ere the relation 

 of opsonins to other bodies in serum can be definitely 

 assigned, but the above results are very definite and of 

 a striking nature. We shall consider in the next section 

 whether the comparatively thermostable opsonin which 

 may be present in an immune serum can be removed by the 

 methods of absorption employed above. In this way we 

 hope to gain some light on the question as to whether there 

 are one or two classes of opsonins, so far as their combining 

 relationships are concerned. 



Note. It is to be noted that these observations refer only to the 

 labile substance of the serum, which is destroyed at 60 C. and 

 without which the opsonic action of a normal serum is practically 

 nil. They leave out of consideration the question whether a small 

 quantity of stable substance of the nature of an immune-body is 

 also concerned. The results obtained have been confirmed by others, 

 , e. g. by Neufeld and Hiine, 1 by Levaditi 2 and his co-workers. An 

 interesting additional confirmation has also recently been published 

 by Browning. 3 Sachs and Teruuchi had previously shown that if 

 a normal serum were diluted with five volumes of distilled water 

 and kept at 37 C. for an hour and a half, then on restoring the 

 original salt content the haemolytic complement was found to be 

 destroyed. Browning found that by the same procedure the com- 

 plement opsonin of normal serum was also destroyed, whereas the 

 immune opsonin (vide infra) was unaffected. 



1 Neufeld and Hiine, Arbeit, a. d. Kais. Ges.-Amt, 1907, Bd. 25. 



2 Levaditi, various papers in Compt. rend. Soc. BioL, 1907. 

 8 Browning, Journ. Med. Research, vol. xix, 1908, p. 201. 



