The Chemical Constitution of the Tubercle Bacillus

Abstract

1. Dried tubercle bacilli extracted with hot solutions of spirit, alcohol, alcohol-ether, Aronson's mixture, yield large percentages of fatty substances.2. On filtering the boiling extracts a white acid-fast precipitate deposits on cooling.3. The filtrates on evaporation can be saponified by soda, and on subsequent agitation with ether and water two extracts can be obtained —an ethereal and a watery extract.4. The ethereal extract contains fat which is not acid-fast.5. By saponifying the dried ethereal extract with alcoholic potash and decomposing the resulting soaps with sulphuric acid a mixture of fatty acids is obtained containing probably oleic, isocetinic and myristinic acids. None of these are acid-fast.6. The watery extract (soap) on decomposition yielded a fatty acid with a melting point corresponding to lauric acid.7. The filtrates also yield lipochromes to which the cultures of tubercle bacillus owe their colour.8. The white acid-fast precipitate obtained by the original extraction can be saponified, but with great difficulty.9. By prolonged boiling with alcoholic potash the acid-fast precipitate is decomposed and results in the deposition of an acid-fast snow-white flaky powder, and a non-acid-fast filtrate of fatty acids.10. The chemical examination of the white flaky powder shows it to be an alcohol.11. Acid- and alcohol-fastness of the tubercle bacillus is due to the presence of an alcohol.