Dominichi Test

DOMINICHI TEST for semen, proposed by D. in 1910. A small amount of the material being tested is placed on a slide and a drop of saturated aqueous solution of tribromide gold (AuBr₃) is added; the mixture is heated to the beginning of boiling and covered with a coverslip. After cooling, when examined at 300-400 times magnification, numerous garnet-red crystals 20-50 μ in size appear in the preparation in the presence of semen, in the form of squares, crosses, and pointed rhombuses. The pointed crystals have longitudinal and in some places transverse striations; some of them are yellow-pink in color. The crystals are easily soluble in alcohol and alkalis, but resistant to mineral acids, even concentrated ones. In polarized light, they show double refraction, and when examined with an ultramicroscope, fine grains are visible in them. According to D., the test works with fresh human semen (even in azoospermia) and with old semen stains. According to Ignatovsky, crystals are not always obtained from semen stains; they form easily from fresh semen. The Dominichi test is preliminary, like the Florence or Barberio test (see Barberio reaction).