and in recovering pneumonia cases^ by the fact that the cell 

 obtained under these circumstances are youngei' than the leuco- 

 cytes in the blood stream of norrual individuals. This suggests, 

 tlisn, that it would not be possible to demonstrate conclu- 

 sively a depression in phagocytic effectiveness without first 

 eliminating the possibility of an increased "cytophagic" index 

 which might even over compensate for the decline in opsonins. 



The results of this investigation would seem to warrant 

 the conclusion that with the possible exception of cases with 

 extreme leucopenia the relative phagocytic power of an infected 

 animal is never lov;er than the opsonic index indicates, but 

 that it is sometimes, indeed it is commonly, very much higher. 

 The opsonic index, with the exception noted above, never does 

 more than express the minimal limitations of the animal's 

 phagocytic defense. 



VvTiile it is manifestly impossible , by any experimental 

 means whatever, to estimate accurately the phagocytic capacity 

 of an animal, it is quite useless to employ the Wright technique 

 unless a correction is made for the observed variations in the 

 number of neutrophile leucocytes present in the experimental 

 animals. The factor by which this correction is made in the 

 following table vjas obtained in each case by dividing the number 

 of neutrophilic leucocytes present in 1 cmmi. of experimental 

 blood by the corresponding count in the control. The vVright . 

 opsonic index is tnen multiplied by tae above factor. This 

 new measure of rela.tive phagocytic capacity may for convenience 



(57) 



