[Influencing factors of previous testing on blood determination (author's transl)].

The demonstration of individual characteristics, especially those of the blood group types are substantially disturbed through the hydrogenperoxide- and the luminol spray procedure, which when it is previously employed, can cause changes in the blood spot. These changes are expecially by very small blood spots to be expected, but even larger ones under intensive spraying can be effected. Only with great caution are such spray procedures to be used and then only if it is impossible any other way to gather information about the existance of blood spots.