Most investigators studying bactericidal and other properties of the fluid
portion of blood have utilized as the test material serum collected following
coagulation of whole blood. Largely neglected has been the concept, emphasized
by some early workers, that substances released from leucocytes or platelets
might impart to the serum activities not present prior to clotting.
For example, Metehnikoff (1) in 1905 discussed as follows some experiments directed
towards this point. "The blood was drawn into paraffined tubes and centfiiugalized
at once . . . . The fluid thus prepared is certainly more allied to circulating plasma than
the blood serum obtained after coagulation of the blood. Neverthdess, it is still far
from being identical with true normal plasma; it still coagulates, though tardily.
Gengou compared, in their bactericidal action, the blood serum and the serum decanted
after the tardy coagulation of the fluid analogous to plasma . . . . I have closely
followed all these experiments and can confirm the results described by Gengou,
namely, t h a t . . , this plasma serum possesses an insignificant bactericidal power or
none at all, whilst the blood serum almost always exhibits this property to a marked
degree."
This communication presents results of studies extending those of Gengou
(2) on the comparative bactericidal properties of blood serum and plasma
serum.1