Tadpoles of Rana nigromaculata were cultured in different population densities ranging from 2 to 50 animals per bowl of one liter of water. Animals raised in crowded bowls inhibited their growth rate as compared with uncrowded groups.
The indication of inhibitory effect was made by measurements of body size and by examinations of gonadal development with respect to representative tadpoles from each experimental group which has variable population density.
The crowding of many individuals together brought on the decline in growth rate and retardation of gonadal development as well as failure in occurrence of metamorphosis.
However the differences in gonadal development among four groups were not strictly proportional with the variation of their body sizes as a result of growth inhibition.