1. Addition of salvarsan to serum in vitro produces a spirocheticidal mixture which is increased in potency by heating. 2. The heated serum of salvarsan-treated patients is more spirocheticidal if it has been in contact with the clot over night than if it has been separated immediately after coagulation. This is not true with the serum from blood which has been salvarsanized in vitro. 3. The ad...
