Summary
In these investigations it was shown that the contact factors of the coagulation system - isolated as in the contact activation test according to Egli or as Celite eluate (Waaler) - do not influence platelet aggregation. Platelet aggregation was measured by the rotation method of Wright.
It was concluded that contact of blood with wettable surfaces leads to activation of the coagulation system and independently to aggregation of platelets. By heating of plasma to 56° a platelet aggregating principle is liberated; the significance of this finding needs further investigation.