PHARMACOLOGICAL STUDIES ON EXPECTORANTS .12. FATTY-ACID COMPOSITION OF PHOSPHATIDYLCHOLINE (PC) IN THE SPUTUM, NORMAL RESPIRATORY-TRACT FLUID (NRTF), MUCIN-LIKE SUBSTANCE (MLS), LUNG WASHING (LW) AND LUNG-TISSUE (LT) AND EFFECTS OF AMBROXOL ON SEVERAL PARAMETERS OF NRTF IN RABBIT,