Many methods have been devised to measure accurately the amount of hemolysis in the end-reaction of the Wassermann test. Notable among these is that of Boas, who makes a set of ten standard tubes, showing hemolysis ranging from 10 to 100 per cent., with which he compares the color of the tube at the end of a given test. So far as I know, however, the Duboscq colorimeter has not hitherto been put to this use.
For most practical purposes the naked eye is sufficiently accurate in reading the end-result of the reaction. By it we can readily determine that the reaction is strongly, medium or weakly positive, but there are cases in which hemolysis is almost complete, in which a more accurate reading is necessary to decide whether the reaction should be called weakly positive or negative, particularly those in which the effects of treatment are being gauged by