168 Messrs. 8. G. Shattock and L. 8. Dudgeon. [| Dec. 21, 
Serum of patient saturated with a very thick suspension of melanin ; 
digested for 24 hours, at 37° C., and centrifugalised. | 
(1) 1 vol: of the clear tluid solobtained ype. ere eee 50 cells 
I< ‘normal:washed cellsi.cit-0e- eee eee eee cere } contained _ 
Toy oy) MelanIM oA tee ce oe ae eee eee Eee ne coee 6 granules. 
, Gi) I vol. of the clear fiuid sojobtaimed-..pae neces 50 cells 
1. %,,.. normal “washed cells? cea... ce eee eee } contained 
1's, tubercle bacilli ..c2c5. ccc eee eee eee 56 bacilli. 
Summary and Conclusions from the foregoing Group of Observations. 
In Observation 1—The saturation with melanin of the immune serum 
from a case of acute peritonitis reduced the phagocytosis (using normal 
cells) from 68 granules of melanin to 28 granules. This result shows that 
a large amount of opsonin has been removed by the melanin, the phago- 
cytosis being reduced to 1/3. 
In Observation 2.—Pulmonary tuberculosis, untreated with tuberculin, 
when the serum was saturated with melanin the phagocytosis (using normal 
cells) was reduced from 22 granules of melanin to 5 granules, showing that 
a large amount of deopsonisation towards melanin had been brought about ; 
the opsonin was reduced to 1/4. 
Towards tubercle bacilli the phagocytosis (using normal cells) in the 
patient’s serum was 155 bacilli in 50 cells. After saturation with tubercle 
bacilli the phagocytosis was reduced to 46 bacilli. : 
How far did the saturation with tubercle bacilli reduce the phagocytosis 
of melanin? The phagocytosis of melanin was reduced from 22 granules 
to 2 after saturation of the serum with tubercle bacilli, 2.¢., the opsonin was 
reduced to 1/11. : 
How far did the saturation with melanin reduce the phagocytosis towards 
tubercle bacilli? The reduction here is from 155 to 113. This is consider- 
ably less than will appear from the following observation :— | 
In Observation 3.—The serum used was from a case of pulmonary. tuber- 
culosis, untreated with tuberculin. When the serum was saturated with 
melanin the phagocytosis (using normal cells) was reduced from 18 granules 
of melanin to 6 granules, showing that a large amount of deopsonisation 
towards melanin had been brought about. 
As in the preceding observation the opsonin was reduced to 1/3. Towards 
tubercle bacilli the phagocytosis (using normal cells) in the patient’s serum 
was 170 bacilli in 50 cells. After saturation with tubercle bacilli the phago- 
cytosis was reduced to 13 bacilli. 
How far did the saturation with tubercle bacilli reduce the phagocytosis of 
= oy 
