TUBERCULOSIS. 215 clean conical glasses and measured therein. The- pro- portion of muco-purulent to fluid matter was noted. Depending upon the degree of viscidity and number of bacilli present in the sputum, a varying amount of 5 per cent, caustic potash solution was added to it (from one- sixth to an equal volume), and after the caustic potash had rendered the sputum perfectly fluid more or less water was added to dilute the mixture. The sputum, having been measured, was poured into a perfectly clean wide- mouthed bottle containing fine sterilized gravel or broken glass. Rinsings of a measured amount of the caustic pot- ash solution were used to free the conical glass from what matter might remain and were added to the sputum. The contents of the bottle were agitated in a shaking machine for five minutes, and allowed to stand until the caustic potash solution had had time to act. As soon as the sputum had become homogeneous an equal volume of water was added, and the whole shaken again. The sputum thus treated was of a pale-green or yellowish- brown color, and contained only small fragments of elas- tic tissue. It was allowed to stand two to four hours, and then shaken again for five to ten minutes. By means of a burette of original design drops of ex- actly equal size were secured and caught upon clean sterile cover-glasses. The drops were subsequently spread into an even film by a very fine platinum wire, while the cover-glass was rotated upon a "turn-table." After spreading, the cover-glasses were laid upon a level brass plate slightly warmed to facilitate drying. After drying, the cover-glasses were coated with a serum film by spraying, and the temperature raised to 8o°-~9O° C. to coagulate the serum and retain the bacteria in place, after which they were carefully stained with carbol- fuchsin and decolorized with a solution of 150 parts of water, 50 parts of alcohol, and 20-30 drops of pure sul- phuric acid. Prior to this the cover-glass was washed in three alcohols and subsequently in water, and if necessary in acid and alcohol again.