Abstract
Methods heretofore employed in testing for growth inhibiting and bactericidal action of the blood on pneumococcus have consisted in suspending small numbers of pneumococci in whole blood, serum or serum-leucocyte mixtures, contained in the capillary pipette, test tube or hanging drop. Results of tests on serum and serum-leucocyte mixtures have shown a general agreement that neither serum nor serum and leucocytes together inhibit the growth of the pneumococcus. Studies on whole blood, however, have resulted in most divergent findings. Certain workers (Wright, Heist and Solis Cohen) report the finding not only of growth inhibition, but also of pneumococcidal activity in the blood of animals resistant to pneumococcus infection. Other investigators, (Barber, Bull and Bartual) using the same methods on the blood of the same and other resistant animal species failed to find anything more than growth retardation. A review of the more important literature on this subject leads one to the conclusion that with the methods heretofore employed it is not possible to demonstrate with any degree of constancy either growth inhibitory or bactericidal activity of the normal blood for the pneumococcus.
It seemed probable to the writers that further information on this subject could be obtained were it possible to work out a method that should incorporate certain conditions under which inhibition of growth with subsequent destruction of the pneumococcus might be expected to occur in the body. In the tissues of the animal body fluid currents operate to bring the leucocytes and implanted micro-organisms into intimate contact. In the capillary pipette or test tube this constant mixing process is ahsent. Growth inhibition and bacteriolysis probably occur only if all the organisms come into contact with and are phagocyted by actively functioning leucocytes.
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