552 Coagulation o£ Blood 



serum, table 2, showed that 225 units of prothrombin and 1.5 units of thrombin 

 were present. From this point on, protlirombin was converted into thrombin 

 very slowly, approximately one-fourth as rapidly as in those previous experi- 

 ments where cells were present. It is quite evident that when cells and platelets 

 are present they do continue for some time to supply thromboplastin, and the 

 latter, in turn, causes a marked increase in the rate of prothrombin conversion. 

 When conversion is rapid (table 1), the "thrombin tide" is high but brief; 

 when conversion is slow (table 2), antithrombic activity predominates more 

 strikingly, and the "tide" is low but more protracted. 



Discussion 



This attempt to view the entire process of clotting from a quantitative point 

 of view is necessarily incomplete. It is now becoming apparent that there is 

 great need for assay methods which are specific for the inhibitors and for 

 thromboplastin. In addition to assay methods, it is important that every effort 

 be made to isolate the various clotting factors in pure form. Already, gratify- 

 ing progress has been made in the case of prothrombin and thrombin, and 

 with these substances in a purified state it has been possible to work with 

 simplified systems, and thus to establish important quantitative interrelation- 

 ships."'^" As other factors are purified and studied in simplified systems, it is, 

 perhaps, not too much to hope that one will be able to plot all of the variables 

 which enter into the clotting sequence. 



REFERENCES 



1. Cullen, G. E., and Van Slyke, D. D.: Proc. Soc. Exper. Biol. & Med. 13:197, 1916. 



2. Warner, E. D.; Brinkhous, K.M., and Smith, H. P.: Archs. Pathol. 18:587, 1934. 



3. Warner, E. D.; Brinkhous, K. M., and Smith, H. P.: Amer. Jl. Physiol. 1 14:667, 1936. 



4. Smith, H. P.; Warner, E. D., and Brinkhous, K. M.: Jl. Exper. Med. 66:801, 1937. 



5. Quick, A. J.: Jl. Biol. Chem. io9:lxx)ii, 1935. 



6. Quick, A. J.; Stanley-Brown, M., and Bancroft, F. W.: Amer. Jl. Med. Scis. 190-501, 1935. 



7. Quick, A. J.: Amer. Jl. Physiol. 1 14:282, 1936. 



8. Ziffren, S. E.; Owen, C. A.; Hoffman, G. R., and Smith, H. P.: Amer. Jl. Clin. Pathol., tech. 



supp. 4:13, 1940. 



9. Warner, E. D.; Brinkhous, K. M., and Smith, H. P.: Proc. Soc. Exper. Biol. & Med. 40:197, 



1939- 



10. Ziffren, S. E.; Owen, C. A.; Hoffman, G. R., and Smith, H. P.: Proc. Soc. Exper. Biol. & 



Med. 40:595, 1939. 



11. Owen, C. A.; Hoffman, G. R.; Ziffren, S. E., and Smith, H. P.: Proc. Soc. Exper. Biol. & 



Med. 41:181, 1939. 

 la. Mills, C A.: Chin. Jl. Physiol. 1:123, 1927- 



13. Astrup, T.: Enzymologia 9:337, 1941- 



14. Mertz, E. T.; Seegers, W. H., and Smith, H. P.: Proc. Soc. Exper. Biol. & Med. 41:657, 1939. 



15. Mertz, E. T.; Seegers, W. H., and Smith, H. P.: Proc. Soc. Exper. Biol. & Med. 42:604, 1939. 



