The clot or coagulam is a dark -reddish-brown ‘scum’ formed mainly by a network of threads in which dead or damaged blood elements are trapped. It is the property of plasma. Normal blood clotting time is 3−10 min. The clot inside the blood vessels is called a thrombus. A moving thrombus is called embolus. In haemophilia (a sex-linked disease) the blood clotting is delayed. According to Macferlane hypothesis, there are 13−factors responsible for blood clotting (or coagulation). The 4−factors are primary and 9−factors are accessory for this process. Primary factors Fibrinogen Prothrombin Thromboplastin (Thrombokinase) Calcium ions  The first 3−factors are proteinaceous in nature. The Prothrombin (II factor) is synthesized in…