THE GROWTH OF YOUNG MICE ACCORDING TO SIZE OF LITTER

Abstract

SUMMARY Four hundred and seven young albino mice produced in 66 litters had an average weight of 1.41 gm. at birth and of 7.14 gnu at weaning time (3 weeks old). These average values vary very considerably, but uniformly according to size of litter. Individuals from litters of 2 and litters of 10 averaged respectively 1.0 gm. and 1.6 gm. at birth, and 4.45 gm. and 11.75 gm. at weaning time. Individuals from the intermediate sizes of litter grade fairly evenly in between these extremes. The whole growth during suckling is in fact inversely proportional to the size of litter. Growth during suckling is characterised by the active phases in the first and third weeks respectively and a comparatively stagnant period in between. These results can all be explained on a basis of differential nutrition.