Abstract
To investigate the infantile signals of laboratory mice a simple and effective method using pups dead from freezing and virgin females has yielded the following conclusions. 1) Dead pups can elicit from a distance the adult to look for them. 2) Younger pups are preferred to older ones for signals that do not need the living condition. 3) The absence of fur gives rise to a preference. 4) Fetuses can elicit some parental response, but pups are more effective.