
1905. ] The Phagocytosis of Red Blood-Cells. 527 
Experiment 5.—The serum of a rabbit, into whose peritoneal cavity red | 
blood-cells derived from the hen had been injected was found, in the com- 
bination : inactivated serum + erythrocytes of the hen + leucocytes of rabbit, to 
bring about a very active phagocytosis of red blood-cells at 37°C. When | 
1 cc. of the inactivated serum was added to the red blood-cells (previously 
washed with 0°85 per cent. sodium chloride solution in order to remove | 
serum) of 0°25 c.c. of hen’s blood, and the whole allowed to remain three | 
hours at 0°, it was found that, after removal of the red blood-cells by centri- | 
fugalisation, the serum after the addition of erythrocytes and leucocytes as | 
above, had lost its power of bringing about phagocytosis. 
Hapervment 6.—The serum of a rabbit, into whose peritoneal cavity red 
blood-cells derived from the calf had been injected, was found in the com- 
bination: inactivated serum + erythrocytes of calf + leucocytes of rabbit, to bring | 
about phagocytosis at 37°. When the inactivated serum was treated with the 
red blood-cells of the calf, as in the preceding experiment, it was found 
subsequently to have lost the power of causing phagocytosis. 
Experiments 7, 8, 9 were similarly carried out with guinea-pigs. which 
received injections of the red blood-cells of the hen, calf, and rabbit respec- 
tively. In each case the inactivated serum employed, which was capable of 
bringing about very active phagocytosis in vitro, after treatment for three 
hours at a temperature of 15° C. with one-quarter of its volume of red blood- © 
cells of the kind used for injection, was found to have lost its power of bringing 
about phagocytosis in vitro. 
Thus the material, the existence of which in serum confers on the latter 
the property of exciting phagocytosis, combines with, or attaches itself to, the 
corresponding red blood-cells, and can therefore be withdrawn from the serum 
in the same way as amboceptor or agglutinin. 
2. On the other hand, as the following experiments show, this material is 
not, in the same period of time, withdrawn from serum to the same extent by | 
leucocytes. 
Experiment 10.—To 0°3 cc. of the serum employed in Experiment 6, 
leucocytes from the rabbit, occupying (after centrifugalisation) a volume of 
about 0°3 c.c., were added. After remaining at a temperature of 37° for three 
hours, the mixture was centrifugalised and to a portion of the supernatant 
liquid, fresh leucocytes from the rabbit and red blood-cells from the hen, were 
added. At the end of an hour at 37° C., phagocytosis was found to have | 
taken place, about 20 per cent. of the leucocytes present having ingested one ~ 
to three red blood-cells. | 
Hapervment 11.—The above experiment was repeated with the serum > 
employed in Experiment 7, about 0:2 cc. leucocytes being added to 0:2 ae. , 
VOL. LXXVI.—B. 2N 
