A BIOMETRIC STUDY OF PHAGOCYTOSIS WITH 
SPECIAL IlEFEllENCE TO THE "OPSONIC INDEX." 
By M. greenwood, Junr., L.R.O.P., M.R.C.S., and 
J. D. C. WHITE, M.A., M.D. Cantab., L.E.O.P., M.R.C.S. 
FIRST MEMOIR. ON THE FREQUENCY DISTRIBUTIONS 
OF PHAGOCYTIC COUNTS. 
{From the Loiiduii Hospital Statistical Laboratory.) 
Perhaps no event since the famous studies of Metchnikoff has done so much 
to concentrate attention upon the phenomena associated with phagocytic action as 
the appearance of Wright and Douglas' papers announcing the discovery of 
"Opsonins" in blood serum*. 
Since the original communications appeared, a literature of respectable dimen- 
sions has accumulated, and controversies, which show few signs of abating, have 
been provoked. 
Looking at the matter from the standpoint of a clinician, it would appear that 
the controversialists are ranged in two camps. On the one hand, Sir Almroth 
Wright and his pupils maintain that we possess in the determination of the 
" opsonic index " not only a reliable means of diagnosis and prognosis in cases which 
cannot be elucidated by the time-honoured methods of clinical examination, but 
the ability to regulate therapeutic procedures with a precision and delicacy which, 
if still leaving somewhat to be desired, have been hitherto unattainable. 
On the other hand, investigators not less numerous and almost as trenchant, 
have asserted that opsonic determinations are altogether unreliable for purposes of 
diagnosis, prognosis or treatment. 
In view of the great practical value which must attach to the method if the 
claims of Sir Almroth Wright be well-founded, we have undertaken an analysis of 
data which seemed likely to yield information of importance as to the reliability of 
opsonic determinations as at present made. 
* Froc. Rot). Soc. 1903, lxii. p. 357 ; 1904, lxiii. p. 728. 
