Isolation of forestream and midstream portions of collected urine samples

A forestream sample of a urine void is isolated from a subsequently collected midstream specimen by means of a valve controlled by material which swells to many times its original volume when exposed to urine. The material is disposed in a forestream receiving chamber having a normally open inlet aperture toward which void urine is directed by a funnel, or the like. Upon contact between the liquid and the material in the chamber, the material absorbs the liquid and swells to many times its original volume while forcefully urging a movable member against the aperture to block further entry of liquid into the chamber. Subsequently received liquid is redirected into a midstream specimen collection container. The void stream is initially received by a funnel having a discharge spout which terminates below the level of an overflow opening from which the subsequently received void portion is redirected into the midstream specimen container.