SOUND RECEPTION 87 



electron-microscopy to be a very complicated cilium-like structure 

 consisting of basal rootlets fusing into a root as they ascend within the 

 dendrite (Fig. 62). Marked periodic cross striations are present. The 

 distal portion of the cilium-like structure consists of nine fibrils 



Fig. 62. Diagrammatic longitudinal section through the sensillum in the 

 tympanic organ of the locust. Cs, scolopale cap ; Ci, cilium-like process ; 

 Sc, scolopale cell; C, cap cell; F, fibrous sheath cell; Sw, Schwann 

 cell; Sr, scolopale rod; D, dendrite. (Redrawn from Gray, 1960.) 



surrounding a central core. Its resemblance to the typical motile 

 cilium is so striking that Gray (1960) called it a cilium. Since there is no 

 evidence that it is functionally a cilium, it seems inadvisable to identify 

 it so completely with those structures. 'Cilium-like' is a more appro- 

 priate designation. 



Mechanism of Action 



It will be recalled that vibrational disturbance in a homogeneous 

 medium produced both a local increase in pressure and a displacement 



