ON THE GENETIC NATURE OF THE TIME OF ATTAINMENT OF PUBERTY IN THE FEMALE MOUSE

¹ Department of Animal Genetics, University of Edinburgh

In the mouse stocks examined it was found that relatively early and relatively late attainment of sexual maturity are genetic characters, and are not influenced in their expression by differences in environmental conditions whenthe animals are kept at an optimum and constant temperature.

Environmental factors (food and general care), however, do condition the pregnancy rate-that is to say, the percentage of pregnancies following upon first mating at the first, second, and third cestrous cycles is determined by non-genetic factors.