PART III 

 INADEQUACY OF THE V^RIGHT TEGHI^tIQUE 



The remaining experimental portion of this paper will 

 be devoted to an analysis of the adequacy of the usual opsonic 

 methods for extimatinn- the phagocytic capacity of an animal. 

 During the course of this investigation there have been several 

 occasions when the opsonic index, determined in the accepted 

 manner, has iven not only an inaccurate gauge of the animal's 

 phagocytic defense but has indicated a result the exact opposite 

 of what was subsequently demonstrated to be the true condition. 

 For these reasons it seems altogether worth while to examine 

 the additional factors necessary to make vJrijht's method a de- 

 pendable technique for determining, so far as it is possible 

 to determine, the true phagocytic strength of an animal. 



Wright (35) has t'emonstrated by a series of experiments 

 which have been repeatedly confirmed that the stimulating ef- 

 fect of serum on phagocytosis is directed almost entirely against 

 the bacteria. And it is reasonable to suppose from Bordet's (36) 

 work tnat whenever one bacterium in a medium has been sufficient- 

 ly opsonized to permit its being taken up by a leucocyte, all 

 similar bacteria oT comparable virulence in that environment 

 will likewise be sufficiently sensitized to effect their engulf- 

 ment. Neglecting, then, the possibility of non-specific absorp- 

 tion of opsonins by the lecocytes, the extent of the subsequent 

 phagocytosis would be determined entirely by the number of phago- 

 cytic cells present. Accordingly, it would be impossible to 



(55) 



