Quantitative complement fixation

Summary In agreement with the investigations ofKentet al. (4), it was found that blood collected in a modifiedAlsevers solution remains constant for a period of at least 14 days.We also succeeded in proving the same with regard to complement, stored according toRichardson (9) and with regard to amboceptor prepared according to the directions of the New York State Department of Health and stored in an equal volume of glycerol at 4° C.The cheap Eel colorimeter proved very suitable for the standardization of the erythrocyte-suspension and the measurement of the percentage of haemolysis.Success was not obtained by means of the method, used in this investigation, to keep the amount of complement, which under the conditions of the test causes haemolysis of 50% of erythrocytes, so constant, as to make daily complement titration unnecessary.