the Influence of Concentration (gibson's Method) on the Presence of Tetanus Toxin in Blood Serum

A number of workers have observed the very interesting fact that during the period of incubation of tetanus, and in some cases during the early symptoms, in certain animals tetanus toxin is present in the circulating blood. Perhaps the most notable of these observations was that recorded by Bolton, Firch and Walden 2 in their' report on the cases of tetanus, including seven deaths therefrom, following the use of diphtheria antitoxin, in St. Louis, in I9oI. These observers found that the serum from a certain horse which was bled for diphtheria antitoxin three days before it was killed, on account of having tetanus, contained tetanus toxin. They found that o.I c.c. of this serum contained sufficient toxin to cause the death of guinea-pigs and that Io c.c. had caused the death of children. The great importance of this danger has been fully recognized and guarded against by all producers of antitoxic sera since that time. It is now as much a routine practice of antitoxin producers to make what is known as safety tests as to make potency tests. A safety test is made by injecting about 5 c.c. of the serum into guinea-pigs and observing the animal for some days, particularly for symptoms of tetanus. Moreover, as one of the causes of the St. Louis accident was the use of serum a few days after being collected and before tests had been made, most producers rarely market serum under six months old.