Abstract
The frequency and degree of the thromboplastic effects of penicillin and streptomycin on the blood of higher animals were studied. Coagulation studies on whole blood were done by the Lee and White (or Howell) method. Amorphous penicillin by any route of admn. markedly accelerated the clotting time. Penicillins G and F were much less thromboplastic than X and K. Penicillin X added to G caused a synergistic effect. Streptomycin was markedly thromboplastic in rabbits and cats.