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Observations upon Phagocytosis carried out by Means of Melanin - 
to Ascertain more particularly whether the Opsonic Index vs 
Identical with the Hemophagocytic Index. 
By 8. G. SHATTOCK and LEONARD S. DUDGEON. 
(Communicated by Professor J. Rose Bradford, For.Sec.R.S. Received 
December 21, 1907,—Read February 6, 1908.) 
(From the Pathological Laboratories, St. Thomas’s Hospital.) 
The following work was taken up in the belief that interesting informa- 
tion might be obtained by the substitution of a finely divided inert substance 
in place of bacteria, wherewith to study the phagocytic index in particular 
infective diseases. The substance which we selected was melanin obtained 
from the eye of the ox. 
The questions which we set ourselves to test by this method we may put 
seriatum ; and we may, after each, recount the particular observations bearing 
upon it, and give the conclusions to be drawn from them. 
Question 1—Will an increased phagocytosis of melanin take place if 
melanin is added to the blood of a patient suffering from an infective 
disease, as compared with normal blood; orif melanin is presented to normal 
washed leucocytes in an immune serum, as compared with a normal serum ? 
To give first the results of the simpler of these two observations. The 
method consisted in drawing up 1 volume of blood into the capillary end of 
,a pipette, and, immediately after this, 1 volume of citrated salt solution 
(1 per cent. sodium citrate, 9 per cent. salt), and thirdly 1 volume of melanin, 
suspended in salt solution. 
The three volumes were discharged from the tube by means of a rubber 
teat fixed to the wider end, mixed in a watch glass in the usual way, and 
finally drawn up the capillary portion of the pipette, the fine end of which 
was then sealed in the flame, and the pipette laid horizontally in the incu- 
bator at 37° C. for 20 minutes; the blood film was thereupon prepared as 
already described. In our later observations we simplified this technique 
by using only two volumes: viz., 1 volume of blood and 1 volume of 
melanin suspended in citrated salt solution, instead of in simple salt. 
Summary and Conclusions drawn from the Observations made to Test 
the First Part of Question (1). 
In a total of 32 cases, the phagocytic index is below par in 8; at par 
in 7; and above par in 17, ascending to 2, 3, 4, 5, 6, and even 8. 
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