A decrease in blood coagulability in anaphylactic shock has been described by Biedl and Kraus (1), Friedberger (2) and others for the guinea pig, rabbit, and dog. Gahringer, however, in the current number of this Journal shows that the change of primary importance as to blood coagulability, is an increase in coagulability concurrent with the acute symptoms of shock and that the decreased coagulability is a negative phase secondary to this increase. An extension of Gahringer's work in this laboratory shows also that the same sequence of changes in coagulability obtains in a great variety of shock reactions induced by the injection of water-insoluble particles such as bacteria, colloidal carmine, lamp black, etc. It would appear then, that during the occurrence of acute anaphylactic and anaphylactoid shock symptoms, there is an increased tendency on the part of the fibrinoplastic substances to undergo those changes which lead to the formation of fibrin aggregates.