ABSTRACT
Blood has intrigued people since ancient times when the transformation of fluid blood to a gel-like mass as it escaped the body was a source of recurrent speculation (1). The earliest reference to bleeding disorders dates back to the fifth-century A.D. Babylonian Talmud, which cautioned that if two male children had died of bleeding after circumcision, the third must not be circumcised (2). The realization that clots stem blood loss did not occur until the beginning of the eighteenth century (1,3) Prior to this some observers hypothesized that blood clotted because it cooled upon exposure to air or that it dried as it left the body (4). It was not until the nineteenth century that the existence of thrombin, the key enzyme in coagulation, was recognized (1).
