Kaiserling's Method

KAISERLING'S METHOD (Kaiserling), a technique for preserving museum pathological-anatomical specimens while retaining their natural coloration; published by the author in 1895, shortly after Melnikov-Razvedenkov described his own method. In its essence, Kaiserling's method is similar to Melnikov-Razvedenkov's method and, like the latter, consists of three phases: 1. Fixation of the specimen in a solution of formalin with salts; here, in addition to fixation by formalin, whose diffusion capacity is enhanced by the addition of an acetate salt, hemoglobin is converted into methemoglobin, which gives the specimen a brown color. 2. Immersion of the specimen in 96–97% alcohol; in the latter, methemoglobin is converted into cathaemoglobin (Kat-Hb),* which restores the specimen's original (natural) color. 3. Preservation of the specimen in a glycerin-acetate mixture. The composition of the fixing fluid in Kaiserling's method is as follows: water—4,000 cm³, formalin—800 cm³, potassium acetate—85 g, potassium nitrate—45 g. The composition of the preservation fluid: distilled water—900 cm³, potassium acetate—200 g, glycerin—300 g. Specimens are placed into the fixing fluid without washing in water, as the latter can extract hemoglobin through hemolysis, and are kept there from 1–2 days to 1 week (depending on the specimen); overkeeping the specimen in the saline formalin beyond this period (e.g., 3–4 weeks) leads to the formation of stable methemoglobin, which does not convert into Kat-Hb in alcohol. The specimen is kept in alcohol for as short a time as possible, namely from 2 to 12 hours, and it is better to use two portions of alcohol, the last of which must be fresh each time. If the specimen is overkept in alcohol, its color quickly fades. Denatured alcohol is not suitable for the purposes of Kaiserling's method. After fixation in saline formalin and after staying in alcohol, the specimen must be washed in running water. In the preservation fluid, the specimen is preserved for an indefinitely long time, provided it is enclosed in a hermetically sealed vessel. * Cathaemoglobin (the obsolete name is "neutral hematin") is a beautiful red pigment, insoluble in water and alcohol, and apparently an intermediate product in the transition of blood pigment into hematin. It is formed by the cleavage of the organic iron-containing complex from hemoglobin or methemoglobin under the action of alcohol and alkalis.