[The influence of soil differences in determining the quantity and recognizability of serological properties of blood traces in the earth (author's transl)].

In order to test the influence of soil differences in determining the quantity and recognizability of serological properties of blood traces in the earth 6 different pedologically examined soil samples of the area of Lower Saxony were impregnated with human blood and tested in two series with reference to the passage of time in dry and damp conditions. The determination of blood quantity by the protein-elution method of Schulz and the cyan-methaemoglobin method of Schleyer was basically possible in all soils. The results of the colour method were more constant and less subject to interference. Decreasing values from 100 down to 13% in the order: sand--Rendsina chalk--garden soil--water meadow loam--clay--humus were to be found, chiefly depending on the size of the particles in the various samples. In damp condition the values dropped to zero after 3 days already. The immediate determination of the ABO blood groups with the absorption technique only proved possible in the case of blood traces in washed sand procesures. One might take NaCl extraction and ascending chromatography on strips of filterpaper or (preferably!) concentrate an initially large quantity of elution fluid. A determination of the Gm factors, however, is only possible on unprepared material. The enrichment procedures often lead to a falsely positive determination of the factors; Testing of ABO groups was most unfavourably influenced by loam, that of Gm by clay and chalk soils. All results may be distrubed by humin-and non-humin substances and any metabolism of microorganisms, which of course is especially noticable in damp humas soil. In practice therefore the samples must be dried as soon as possible.