In pursuance of studies on the coagulation time of blood in the new-born clinic of the pediatric department, University of Minnesota, there was found a host of methods from which to choose, none of which were particularly adapted to the work or gave dependable results.
Since Vierordt's early studies on blood coagulation many ingenious devices and methods have been employed. Hinman and Sladen1 gave a history and résumé of the work. The more practicable of these methods fall into certain types, and these were studied.
First, was considered Wright's2 method and its many modifications. These, however, call for the use of special, carefully calibrated tubes with very close temperature control. Even so, results vary widely. Another type of method was introduced by Milian3 and modified by Duke, Hinman and Sladen.1 This method, however, gives marked variations according to the quantity of blood deposited on the slide,