1. or 2 serotonin in a 10 ml. clot. A white thrombus contains many more platelets than a blood clot, but it is probable that most of the serotonin is released from the platelets as they are laid down in the thrombus. The serotonin content of thrombi;g. Jaques, 1954, Sanders,1959
2. have shown that emboli of small, fresh blood clots produce greater changes in respiratory rhythm and in the mechanical properties of the lungs than do large thrombi,1963