ENDOSMOMETER

(Or. i.^offuof,;, and ^£T««y, measure.) In Physiology, an instrument invented by M. Dutrochet, to measure or demonstrate the rapidity with which one or other of two mixing fluids, of different densities,will pa into each other: and by which the le dense fluids are shown to pa with greater rapidity into the more dense fluids, than vice vers a; in other words, that " endosmosis " is more rapid than " exosmosis." A simple form of the instrument is a graduated tube, expanded into a bell at one end, over which a portion of membrane may be tied. If the bell be filled with a fluid of much density, such as a strong solution of salt, and be immersed in one of le density, as water, the water will endosmose, or pa into the solution more rapidly than the solution will exosmose or pa out. But if the water were put into the bell and the saline solution outside, the directions of the currents would be reversed. In both cases, however, the currents would continue until the two fluids were equally mixed on both sides of the membrane. [s. 1382]