VITAMIN A IN THE VISION OF INSECTS.

Acetone-methanol extracts of honeybees (Apis mellifera) were chromatographed from petroleum ether on columns of aluminum oxide and magnesium oxide:celite. Vitamin A(1) was identified by the Carr-Price (antimony chloride) reaction. These experiments provide the first demonstration of vitamin A in the tissues of an insect. Like retinene, vitamin A is confined to the heads and is not found in either thoraces or abdomens. Dark-adapted bees have very little vitamin A. During light adaptation the vitamin A increases, but at the expense of retinene, which decreases. As much as 0.1 microg of vitamin A/gm of heads has been recovered from light-adapted bees. Two methods are described for demonstrating the enzymic reduction of retinene to vitamin A, using an extract of the heads of honeybees.