INHIBITION OF THE STIMULATING EFFECT OF RED LIGHT ON TESTIS ACTIVITY IN STURNUS VULGARIS (STARLING) BY A RESTRICTED DIET

Abstract

Effects of exposures of 6 hrs. per night to red and green light of about 1.7 foot candles upon testis activity of starlings on varied adequate diets were compared with those of similar exposures to lights of about 2.66 foot candles on a diet restricted to "middlings mash," low in proteins, fats, vitamins and salts, and with controls on complete diet without experimental light exposures, between Dec. and Feb. On complete diets, red light exposures for 23 days induced large increase in testis and tubule size, with metamorphosing sperms; with the same bulbs at intensity weakened by use, to a slightly smaller effect in 25 days. On the restricted diet, increase in testi]s and tubule size and spermatogenic activity was relatively slight in 22 days, with only slight multiplication of spermatogonia. On both diets, green light slightly reduced testis size and activity, as compared with controls. This is taken to indicate that restricted diet limits the response to stimulation of testis activity by light in starlings in winter and spring, and is discussed in relation to other cases of interference of dietary deficiencies with reproductive activity and with the action of anterior pituitary hormones, and to cases where long-waved light increased such effects and short-waved light inhibited them.