The Haemagglutination Inhibition and the Hogben Test in Pregnancy.

Haemagglutination inhibition tests are easy to perform and easy to read. The results are reproducible and are not subject to the vagaries of supply and temperament inherent in tests using living creatures. In a series of tests with Prepuerin done in parallel with the Hogben test the former has shown a higher sensitivity. There have been three false positive results with Prepuerin tests in the series but it was not established on general grounds that pregnancy was not in fact present.