tuberculin (tu-ber'ku-lin)

A preparation made by R. Koch and considered by him to be a means of diagnostic at ing and curing tuberculosis. An extract made with glycerin of cultures of the tubercle bacillus. It is injected subcutaneously and is now employed chiefly as a diagnostic test and curative method, crude t. A glycerin extract of the toxic substances present in cultures of the tubercle bacillus in veal broth containing i per cent, of peptone and 4 or 5 per cent, of glycerin. The culture liquid is evaporated and filtered, modified t. Crude t. that has undergone various changes by the precipitation of certain constituents or filtration, or in which the mode of preparation is changed, modification. old t.as See in Koch's crudefirstt. residual t. The sediment left when a watery extract of triturated tubercle bacilli is submitted to the action of a centrifuge. T. A. is made by extracting the tubercle bacillus with 10 per cent, normal caustic soda, filtering and neutralizing. T. O. (Tuberculin Oberschicht). This substance is prepared by making suspension of dried tubercle bacilli in distilled water and centrifugal i zing this mixture. A sediment is formed and the supernatant liquid, which remains opalescent^ is known as T. O. T. purified is a precipitate from t. made with 60 per cent, alcohol, which is redi olved. T. R. (Tuberculin Riickstand). The deposit from T. O. is dried and centrifugalized, and the supernatant liquid is T. R.