“…Later, with a 1 in 30 suspension, complement fixation occurred in eighteen out of twenty sera from patients diagnosed clinically as suffering from L.G.V. Melczer and Sipos (1937), reviewing previous results, concluded that antigens varied in their potency according to the amount of virus present. Attempts to overcome this difficulty by preparing antigens from infected mouse brain, or guinea-pig or rabbit lymph nodes were not successful.…”