ESTIMATION OF THE OP SON 1C CONTENT OF THE BLOOD 221 



scarcely be of much value in the treatment of infections. For 

 unless we can influence the aggressive forces of the invading organ- 

 isms and notably their capsule-forming power, the production of a 

 high content of opsonins in itself would lead to nothing. 



In conclusion, I would briefly call attention to the fact that in 

 the early days of the opsonic "high tide" I advocated a different 

 method of estimating the opsonins, which was based upon the prin- 

 ciple of dilution, and I note with satisfaction that this principle is 

 now utilized in practically all laboratories (outside of Wright's) in 

 which opsonic studies are being carried on. 



