OPSONIC ACTION 191 



may be increased by immune-bodies leading to the union of 

 more complement. There is in addition, however, the 

 formation of immune opsonin (bacterio-tropin), which pro- 

 duces an opsonic effect by itself. This substance has 

 accordingly the constitution of an agglutinin ; it is left an 

 open question whether, and if so, to what extent, it may 

 lead to the union of complement that is functionate also as 

 an immune-body. 



