The importance of chemical communication in the reproductive behavior of rodents is well documented. Van der Lee and Boot(1955,1956) found that females housed together in groups fail to show the expected 4-day estrous cycle. All cycles were found to be interrupted and delayed, Whitten(1956) Points out that the presence of the male house mouse confined within the female's cage can effectively reduce the number of abnormal cycles.The following experiments was designed to investigate, in more detail, the diffe...