Summary
1. Purified brain tissue thromboplastins of human, bovine and chicken origin have
been tested on homologous and heterologous plasmas.
2. Purified brain tissue thromboplastin is species specific.
3. Lipid extracts from purified brain tissue thromboplastin prepared with pyridin
show a negligable residual species specificity, probably caused by a slight contamination
with brain tissue thromboplastin.
4. The activity curves of our lipid extracts differ from typical curves expected for
lipid activators by a less distinct inhibition in high concentrations probably caused
by a different composition of petrol-ether and pyridin extracts.
5. The protein part of tissue thromboplastin does not activate prothrombin in any
system.
6. The protein part of tissue thromboplastin of one species could be combined with
the lipid part of another species to form an active tissue thromboplastin.
7. The species specificity of these combinations was determined by the source of protein
used.
