Potato

(po-ta'-to). The tuber of Solanum tuberosum. P. -brandy, a brandy distilled from a mixture of potatoes and barley-malt. P. -blight. Same as P. -rot. P. -culture, a culture of microorganisms on potato. Several methods have been employed, the one now in general use being that known as Bolton and Globig's. It is as follows: Cylinders are cut with a cork-borer out of the center of large potatoes, trimmed of skin and imperfections, and cut obliquely, so as to make two wedge-shaped pieces. These are placed in sterile test-tubes with the thin end upward. The tubes are then sterilized for twenty minutes on three succe ive days. In Esmarch's method, slices of potato are placed in small sterilized gla dishes, and the latter, with the contained discs of potato, are sterilized in the steam sterilizer for an hour. In the original method potatoes were cleaned, then soaked in 1 to 1000 mercuric chlorid solution, and finally steamed for an hour. They were then carefully cut with a sterilized knife and allowed to fall apart in a moist chamber. Whichever method is used, the inoculation with the bacteria is the same, namely, by means of the Oese or sterilized needle dipped in the material to be cultivated. P.cure. See Cure . P.-disease: 1. Same as 2. A French term for tuberculosis in cattle. P.fungus, the cause of P. -rot, q. v. P.-mold. Same as P. -rot. P. -murrain. Same as P. -rot. P.paste, a substitute for the solid potato as a culture medium for bacteria, when a very extensive surface is desired. It is a stiff paste made with water from the dry, floury centers of well-boiled potatoes. P. -rot. See under Mildew. P., Spanish, P., Sweet, the tuber of Ipomea batatas. P. -spirit. See Alcohol , Amy I. P. -sugar, a sugar obtained from potatoes. P.-treatment. Same as P. -cure. Efficacy.