ESTIMATION OF THE OPSONIC CONTENT OF THE BLOOD 227 



The idea of proper vaccination, then, is to so gauge and interspace 

 the different doses that a negative phase is obviated as far as possible 

 and a "high tide" of increased opsonic content secured. 



It would lead too far to discuss the teachings of Wright in any 

 detail at this place; suffice it to say that nearly all investigators who 

 have busied themselves with his technique have come to the con- 

 clusion that the unavoidable sources of error are such that accurate 

 results cannot be obtained. As a consequence its application loses 

 much of its raison d'etre, and at the present time there are few outside 

 of Wright's own circle who are influenced in either diagnosis or 

 treatment by the opsonic index. But this failure does not in the least 

 diminish the importance of the principle of bacterial vaccination, 

 a principle which had, however, been firmly established long before 

 the opsonins were descovered. 



It would, of course, be most desirable to possess an index to 

 dosage and frequency of injection in vaccination 1 , but a consideration 

 of what has already been said regarding the aggressive forces of 

 the bacteria will at once suggest that even if it could be possible 

 to estimate the "opsonic index" with accuracy, this alone would 

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

 we can influence the aggressive forces of the invading organisms 

 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. 



BIBLIOGRAPHY. 



Reiter, H. Vakzinetherapie und Vakzinediagnostik, Jahresb. u. d. Ergeb. d. 

 Immunitatsforsch., 1912, viii, 180. 



Frankel, C. Schutzimpfung und Impfschutz, Marburg, 1895. 

 Weichardt. Moderne Immunitatslehre mit besonderer Berticksichtigung d. 

 f. d. praktischen Arzt wichtigen Immunisierungen, Munch, med. Woch., 1901. 

 Wright, A. E. Vaccine Therapy: its Administration, Value, and Limitations. 

 A Discussion. Longmanns, Green & Co., London, 1910. 

 On Vaccination Against Smallpox: 



Jenner, E. Investigations on the Causes and Action of Cowpox, 1799 and 



1800. 

 Pfeiffer, L. Jennerliteratur, Petersburg, Ricker, 1891. 



