It is well known that the serum and plasma proteins usually produce inhibition of hæmolysis by saponin, the bile salts, the soaps, and other related lysins. As early as 1908, however, Sachs described an acceleration of hæmolysis as occurring when serum or plasma is added to systems containing sodium oleate, after the oleate had been in contact with the cells for some time. The same effect was later observed, under certain conditions, by Ponder for sodium glycocholate (1922), for sodium taurocholate (1923), and for stearates and oleates (1924), and also by Sen and Mitra (1928) in systems containing taurocholate, although Sen and Sen (1928) had previously failed to obtain it. It is known from these investigations that the concentration of taurocholate, etc., used, the quantity of serum or plasma added, and the time for which the lysin is allowed to react with the cells determine whether, and how great, an acceleration replaces the more usual inhibition, but otherwise the kinetics of hæmolysis in these systems is obscure. They are of interest, however, because of their resemblance to colloidal silicic acid-complement and brilliant green-serum systems, in which the cells react with the lysin only after being acted on by a sensitizing agent, and in which, as in these systems, the order of addition of the various components largely determines the final result (see Ponder, 1928, 1932,
a
, 1933). It has been already suggested, indeed, that the taurocholate acts by sensitizing the cells to the lytic action of the subsequently added serum, as well as by producing lysis itself, just as brilliant green brings about a similar sensitization, and is, in sufficient concentration, a lysin
per se
(Ponder, 1934,
a
). The only other suggestion which has been put forward is that of Sen and Roy (1930-31), who observe that either an inhibition or an acceleration can be obtained by adding various amines to systems containing sodium taurocholate, the result depending on whether the addition is made before or after the taurocholate has come into contact with the cells. Since the addition of the amines makes the systems containing cells and taurocholate more alkaline (the
p
H
of such systems usually being between 5·0 and 6·0), Sen and Roy suggest that the similar accelerating effect of serum may be due, in part at least, to its alkali content.
THE EFFECT OF HEMOLYTIC SUBSTANCES ON WHITE CELL RESPIRATION