With acridinorange it is possible to stain selectively trypanosomes in blood intra-vitam. In subsequent examination by means of a fluorescence microscope only leucocytes and trypanosomes are visible (as shining bright green bodies), while the erythrocytes are not visible. Living and dead trypanosomes, too, may be distinguished in this way.With the fluorescent dye auramine, trypanosomes in blood may be selectively stained (showing up in golden fluorescence) so that diagnosis for trypanosomes is very greatly facilitated. Even in difficult cases a decision on the presence of trypanosomes in blood is possible.