LEUCOCYTOSIS AND OPSONIC CONTENT OF SERUM 41 



VI. — Summary and Conclusions. 



1. The opsonic content is uninfluenced by the presence of hyper- 

 leucocytosis, or relative neutrophih'a in the circulating blood, when these 

 conditions are brought about by the injection of simply-constituted 

 chemical bodies, like sodium cinnamate, tallianine, pilocarpine, etc. 



2. The opsonic content is very markedly influenced by the 

 inoculation of substances like nuclein, autolysed cultures, etc., the 

 chemical constitution of which is exceedingly complex, and probably 

 closely akin to that of the bacterial proteines. These substances at the 

 same time produce decided changes in the blood picture, though these 

 are, as a rule, less marked than in the case of the simpler bodies above 

 mentioned. 



3. During the period of hyperleucocytosis, the phagocytic power of 

 the neutrophile leucocytes is considerably reduced. 



Naturally, we have considered whether any conclusions can be drawn 

 from the above-mentioned experiments, in reference to the important 

 questions of the origin, and probable nature, of the opsonic substances in 

 the serum. 



In the first place, it is improbable that the substance is of the nature 

 of complement, otherwise one might have expected an increase of the 

 opsonic content of the serum, after the inoculation of substances like 

 sodium cinnamate, which are known to raise the haemolytic complement 

 content concurrently with the production of a neutrophilic leucocytosis. 



On the assumption that the opsonin is of the nature of an interme- 

 diary body which manifests its full action when co-operating with a 

 complement, the results might be more readily explained. Thus, even 

 with complement-increasing substances, like sodium cinnamate, it might 

 be supposed that there is always just sufficient normal complement to 

 neutralise the available amboceptor, and hence no opsonic rise would be 

 recorded. The injection of substances like nuclein, of highly complex 

 chemical constitution, and possibly allied to bacterial proteins, might 

 produce an increase of intermediary body. The effect on the leucocytes 

 might at the same time produce an increase of complement, and thus the 

 opsonic content might rise. A third possibility is that the opsonin is a 



(361) 



