That malarial parasites produce a poison was first suggested by Golgi, and since then has been assumed as probable by many investigators. So far, no one has in any way described or demonstrated this poison. Its existence is assumed only to explain some of the symptoms (as, for instance, the paroxysm) that could not be explained without it. The toxicity of the malarial urine (see another section) may be considered the only concrete factor thus far discovered that points to a malarial toxin.
I have recently endeavored to prove this question in this way: I took the blood of two patients during a paroxysm, centrifugated it, and injected subcutaneously the pure serum into healthy men. In the first case I employed 1 c.c. of serum (ordinary tertian). The temperature of the person experimented on was at the time of the injection (4 p. m.) 36.7°; at 4.30p.m., 37°; at 6 p.m., 36°. In the second case I injected 0.7 c.c. of the clear, canary yellow serum (likewise tertian); the temperature of the person experimented on rose within fifteen minutes from 36.5° to 37.6°.
These experiments should be continued with larger quantities of serum in order to arrive at positive results. Bignami doubts the existence of a free malarial toxin, because he found the blood of the fetus of a pregnant woman infected with malaria normal.