Limes

LIMES (Latin: boundary), a term denoting that dose of toxin which, when mixed with a certain amount (measured in antitoxic units) of corresponding antitoxin, causes one of the following four reactions: 1. Limes Null, L₀-the amount of toxin which, when mixed with one unit of antitoxin (1AE), produces no local or general pathological phenomena in a 250-gram guinea pig upon subcutaneous injection due to the "neutrality" of the mixture. 2. Limes mortis, limes Tod, L_t-the dose of toxin in which, after mixing with 1AE of the corresponding antitoxin, there remains a free amount of toxin sufficient to kill a 250-gram guinea pig in 3-5 days upon subcutaneous administration. This amount corresponds to one minimal lethal dose (dosis letalis minima, Dl_m), also called the direct lethal dose of the given toxin, as opposed to L_t, the indirect lethal dose. 3. Limes necrosis, L. nec.-a term used in Romer's reaction to denote the smallest amount of toxin (diphtheria) which, when mixed with Veo or ^x/_ьо or ^x/₁₀₀ of an antitoxic unit, produces local necrosis in a guinea pig upon intradermal injection. 4. Limes flocculatio, Lf-the dose of toxin which, when mixed with 1AE of the corresponding antitoxin, gives in vitro the most pronounced precipitation of flakes, flocculation (Ramon reaction). This value in fresh toxins almost coincides with L₀.--Limes reducens-a term introduced into microbiology by Neisser and Wechsberg for denoting that dose of dye, mainly methylene blue, which is reduced by a certain amount of an emulsion of living cells, for example, leukocytes. Lit.-see foreign literature under the article Control of bacterial preparations.