ABSTRACT
An earlier paper (Rowell, 1961a) described a reflex cleaning or grooming movement by the front leg in Schistocerca gregaria; it is evoked by stimulation of the sensilla of the prothoracic sternum. In the unrestrained animal this response can only rarely be seen, but under experimental conditions it can be obtained reliably if the connectives uniting the prothoracic ganglion to the rest of the C.N.S. are cut, provided that the tarsi of the front legs are not allowed to contact anything. Under all other conditions the reflex is partially or completely inhibited.
In the 1961 paper I claimed that the number of sensilla greatly exceeded the number of axons and that therefore some fusion of axons must take place. This is wrong. Electron micrographs show 1200–1500 axons in each of the nerves where they join the ganglion, which is enough to account for all the sensilla. Many are small, less than 1 μ diameter, and were not seen with the ordinary light microscope in the earlier sectio—
