Moist Chamber

MOIST CHAMBER, a device for the long-term observation of living objects, bacteria, fungi, protozoa, cells, tissues, tissue cultures, etc., under a microscope. There are many types of moist chambers, the general principle of which is to prevent the drying out of the object under study without, at the same time, hindering its direct observation. In its modern form, the moist chamber is designed mostly according to the hanging drop type (see). It was first proposed by Kühne (1864–66) and, in the modification by Böttcher (1865–66), consists of a glass ring 1–3 cm in diameter and 5–6 mm high, glued to a microscope slide. The bottom of this chamber is moistened with water, the chamber is covered with a coverslip, on the underside of which the object under study is placed in a drop of liquid. A very common type of moist chamber is that proposed by Koch (1875) for the study of anthrax, which consists of a microscope slide with a depression. The Tanhoffer chamber (1872) is another modification of the moist chamber, consisting of a microscope slide with an annular groove that is filled with water. A very convenient and accessible device is the Strassburger moist chamber (1878–97). Instead of a glass ring, he places a cardboard frame on the microscope slide, over the opening of which a coverslip with a hanging drop is placed. The frame is moistened with water, as a result of which it adheres tightly to the microscope slide, and the necessary humidity is maintained inside it. More complex chambers were designed by Recklinghausen (1863). They are flat, thin-walled glass chambers with inlet and outlet tubes. Chambers of this type can also serve for the study of an object in an atmosphere of various gases. In addition to the moist chambers described, a moist chamber called the "Carrel flask" (Carrel, 1926) is currently used specifically for the cultivation of vertebrate tissues outside the organism. It is a flat, rounded flask 5–8 cm in diameter; its top can be covered with a special, well-ground lid. A neck 3 cm long and 1 cm in diameter extends from the side at an angle, which is plugged with cotton wool and covered with rubber. Plasma is poured into the flask through the neck, a piece of tissue is placed inside, and it is covered with tissue extract. After a certain time, the extract is replaced with fresh extract. For a moist chamber for microoperations, see Microoperations.