It has been shown by numerous observers, especially Wooldridge1 and Morawitz,2 that tissue extracts, such as those obtained from grinding up liver, kidney, muscle, etc., with salt solution, have a marked accelerating action on the coagulation of blood. Artus3 has demonstrated that if salt solution was simply allowed to run over the surface of tissue which has been rendered as free as possible from blood the salt solution acquired an accelerating action. And if the solution of salt were run over the surface more than once, the accelerating properties of the salt solution increased in proportion.
This substance, or perhaps it would be better to say, these substances, although they have never been identified, have been given the name thrombokinase or zymoplastic substances.
And it was these to which Sahli4 referred to in 1905 when, after a most careful study of hemophilia in all its aspects