THE EFFECT OF TOTAL DARKNESS ON THE GROWTH OF THE NEWBORN ALBINO RAT

Abstract

The body wt. and length of the animals reared in darkness were found to be significantly smaller than those of litter-mate controls, the difference being present at the 18th day of post-natal life. Thereafter, until the 30th day, the animals reared in darkness remained consistently smaller than their controls. From the 18th to the 30th days of life, the testes of the exptl. males grew less rapidly than those of the controls although, in relation to body wt., the testes of the exptl. animals were heavier than those of younger control animals of similar wt. The rate of growth of the ovaries of females reared in darkness was found to be significantly less than that of the control ovaries. The retarded growth peculiar to the first 18 days of life suggests a deficiency in lactation. The mothers in the dark consumed less food than the controls.