Here is the first of a series of reports by groups of outstanding investigators in specified fields which are sure to become indispensable aids to true students of medicine. The careful selection of the contributors and the fundamental nature of their presentation will appeal to those readers who are seeking authentic, practical information. For instance, "Blood Clotting and Hemostasis" is presented by L. B. Jaques, of Canada, "Fibrinolytic Enzymes" by Tage Astrup of Copenhagen,
"Initiation and Acceleration Factors in Thrombosis" by K. M. Brinkhaus, "Protein Equilibrium Reactions in the Blood-Clotting Mechanism" by W. H. Seegers and A. G. Ware and "Dicoumarol and the Estimation of Prothrombin" by Karl Link, and there are others of equal importance. The discussion of the papers by the other members of the group adds great interest and clarification.
In an extensive appendix the exact procedures for prothrombin determinations which are carried out in the various