Landmark article Dec 23, 1922. Medicolegal application of human blood grouping. Third communication. By R. Ottenberg

The best technic for the tests is the open slide method. The sources of error are: (1) deteriorated serums; (2) weak serums; (3) hemolysis; (4) incubation at 37 C.; (5) drying; (6) settling of cells; (7) microscope observation; (8) dense cell emulsions; (9) undeveloped group characters, and (10) autoagglutination. On account of these, the following precautions must be observed: (a) Every test must be done in duplicate, using different sets of test serums. (b) Test serums must be shown to be active at the time of the tests. (c) Wherever there is the possibility of doubt, both serum and cells of the individual must be tested. (d) The cell emulsion without addition of test serum must also be examined. In studies of human heredity, the accidental inclusion of cases of illegitimacy can best be avoided if the mother of each family fully understands the object of the examinations and consents to them. Buchanan's failure to confirm the hereditary nature of the blood groups is apparently the result of errors of observation. He disagrees with all other authors, who are unanimous in their findings and have recorded almost a thousand cases.