Fig. 212.—Botterill’s Live-trough.
Fig. 213.—Glass Trough.
Glass troughs for chara and polypes (a sectional view of one shown at [Fig. 213]) are made of three pieces of glass, the bottom being a thick strip, and the front (a) of thinner glass than the back (b); the whole is cemented together with Jeffery’s marine-glue. The method adopted for confining objects near the front glass varies according to circumstances. The most convenient is to place in the trough a piece of glass wide enough to stand across diagonally, as at c; then, if the object be heavier than water, it will sink until stopped by the glass plate. At other times, when used to view chara, the diagonal plate may be made to press it close to the front by means of a wedge of glass or cork. When using the trough the microscope should be placed in a nearly horizontal position.
Fig. 214.—Weber’s Slip with Convex Cell for use as a Live-trough.
Fig. 215.—Current-slide Live-cell.
Cells for viewing living objects, and watching their movements, take many forms, usually determined by the makers for the purposes they are required to serve. The smaller glass troughs (Figs. 216, 216a) are made for examining the small infusoria, rotifers, &c., some of which take special forms, as the double or divided trough ([Fig. 217]) intended for viewing the circulation of the blood in the tail of a small fish, and at the same time keep up a supply of water and air.
