Responses of tarsal hairs of the bluebottle, Calliphora erythrocephala Meig., to sugar and water

Abstract

Using a specially designed high-input impedance a.c. preamplifier it was possible to record the responses of tarsal chemoreceptive hairs of Calliphora erythrocephala Meig. to pure sucrose solutions (0·5 M, 0·1 M, and 0·02 M) and water. Sugar always evoked two types of impulses of which the smaller one probably originated in a water receptor, whereas the larger one was fired by a cell sensitive to sugar. In about 90 per cent of the water stimulations two types of spikes were recorded. The larger of these spike types was presumably fired by a water receptor. The possibility that the smaller type of water spike was discharged by a cation or anion receptor, or represented spontaneous activity in any of the sense cells at the base of the tarsal hairs, is discussed. In the remaining 10 per cent of the water stimulations we probably recorded spikes of a water cell only.