SITUATIONAL DETERMINANTS OF OPEN-FIELD BEHAVIOUR IN MUS MUSCULUS.

A cross of eight inbred lines of albino mice was made in order to construct a heterogeneous sample representative of the laboratory species. An experiment incorporating the factors of light, noise, arena size, sex and days was performed using an open-field test standardized on the rat. The results obtained were compared with previous findings on inbred lines and F₁s. Ambulation was markedly affected by most independent variables, whilst defaecation seemed less sensitive in relation to them. The utility of multiple crosses of inbred lines is discussed. [ABSTRACT FROM AUTHOR]