212 A MANUAL OF BACTERIOLOGY 



The first effect of the injection is to cause a fall in the 

 opsonic index, the " negative phase " of Wright, which 

 is usually afterwards followed by a rise, and by properly 

 spacing the injections a considerable rise in the opsonic 

 value may ultimately result. If too much vaccine be 

 given the effect may be to permanently depress the index 

 and cause harm instead of good, hence the desirability of 

 controlling all injections by determinations of the opsonic 

 index. This, however, renders the treatment very labo- 

 rious, and generally by employing small doses and allowing 

 at least a week to elapse between the doses, determina- 

 tions of the opsonic index are unnecessary (for dosage, etc., 

 see p. 221). By movement, massage, etc., applied at or 

 about the seat of a local infection, bacterial products are 

 disseminated which may alter the index ; a process of 

 auto-inoculation may thus result. 



The opsonic index may be used for diagnostic purposes ; 

 a low or high opsonic value towards a particular organism 

 suggests that an infection by this organism exists or has 

 recently existed. 



Bulloch came to the conclusion that the blood contains 

 a number of specific opsonins, one for tubercle, another for 

 M. pyogenes, and so on. Simon, Lamar, and Bispham, 1 

 however, from a number of carefully devised experiments, 

 conclude that specificity of opsonins does not exist, and 

 suggest that opsonins may be a constant quantity, and 

 that the number of organisms taken up by the leuco- 

 cytes is influenced by a second unknown and variable 

 factor. 



Russell 2 also concludes that in normal serum the opsonins 

 are " common " and not specific, \nnd can be removed by 

 a number of bodies. In immune serum, on the other 

 hand, both "common" and "immune" opsonins are 



1 Journ. Exper. Med., vol. viii, 1906, p. 651. 



2 Johns Hopkins Hosp. Bull., vol. xviii, 1907, p. 252. 



