A Preliminary Study of Six-Hour Rat Test for the Diagnosis of Pregnancy

sitive to prolan (the anterior pituitary-like hormone), than the immature female mouse, the rat has been tried as an experimental animal for pregnancy-hormone tests. Eberson and Silverberg (1931), who used immature rats, obtained results as early as thirty-six to fortyeight hours. Walker and Walker (1938) modified the above test and reduced the time to thirty hours. Later, Kelso (1940), and Frank and Berman (1941) published reports on a twenty-four-hour modification, using rats for the diagnosis of pregnancy. The author (1944) confirmed the reports of the above workers on their twenty-four-hour modification, and strongly advocated the use of an immature female white rat as an addition to other test animals, such as the rabbit and the mouse. The twenty-four-hour test period was reduced further to six hours on the basis of which Salmon and his co-workers (1942) established