526 Dr. J. O. Wakelin Barratt. [July 14, 
On the 30th day blood was taken from the animal and serum obtained. To 
a small amount of this serum (which when active was strongly hemolytic), 
after inactivation, leucocytes from the guinea-pig and erythrocytes from the 
calf were added. At the end of half an hour, at 37° C., one-quarter of the 
leucocytes present were found to contain one to three or more red blood-cells. 
On testing the agglutinating power of the serum, as in the preceding experi- 
ment, no agglutination was observed in any of the test-tubes, even at the end 
of 24 hours. 
Experiment 4.—Into the abdominal cavity of a guinea-pig the red blood- 
cells obtained from’ the following amounts of goat’s blood were injected: 
on the 1st day, 10 c.c.; on the 6th day, 12 cc.; on the 31st day, 12 cc.; on 
the 41st day, 15 cc. On the 49th day blood was taken from the animal and 
serum obtained. To a small amount of this serum, after inactivation, 
leucocytes from the rabbit and erythrocytes from the goat were added. At 
the end of half an hour at 37° C., well-marked phagocytosis had occurred, 
about one-third of the leucocytes containing red blood-cells; at the end of an 
hour more than three-quarters of the leucocytes had taken up red cells, which 
were observed to be more or less pale. On testing the agglutinating power of 
the serum, as in Experiment 3, no agglutination was observed in any of the 
test-tubes, even at the end of 24 hours. | 
From these experiments it follows that the presence of agglutinin is not a 
necessary factor in the production of phagocytosis. 
The former of the above conclusions is confirmed by the behaviour of 
normal rabbit serum. This has a marked hemolytic action on the red blood- 
cells of the goat and guinea-pig. Nevertheless in the combination : inactivated 
normal rabbit serum + erythrocytes of goat + leucocytes of rabbit, and 
inactivated normal rabbit serum + erythrocytes of guinea-pig + leucocytes of 
rabbit phagocytosis im vitro does not occur, so that in normal serum the 
presence of amboceptor is insufficient to bring about phagocytosis. None of 
the normal sera employed possessed a powerful agglutinating action upon any 
of the red blood-cells employed, so that a similar demonstration of the ineffi- 
ciency of agglutinin cannot be given. 
Since the sera of animals into which red blood-cells have been injected is 
capable of bringing about phagocytosis when amboceptor and agglutinin are 
absent, it follows that this property of such sera is due to some special sub- 
stance which is not amboceptor or agglutinin, 
Respecting the nature of this special substance, the following further data 
are available :— 
1. The substance in question is, as is well known, withdrawn from the sera 
by red blood-cells of the kind used for injection. 
