110 V. G. DETHIER, J. R. LARSEN AND J. R. ADAMS 



cuticle such as occur in the grasshopper (Shfer et al., 1959). As in the 

 grasshopper, the epicuticle does not extend beyond the opening. At the 

 base of the pit in flies, there is a tissue which appears as fine filaments 

 aligned perpendicular to the surface. Similarly in the grasshopper there 

 are about 24 filaments to an opening, and they extend well up into the 

 opening. According to Slifer et al. (1959) these are actually terminations 

 of the dendrites. It has not been possible to ascertain whether or not this 

 is the case in the sensilla of flies, but because of the similarity in other 

 respects it hardly seems likely that the fly and the grasshopper sensilla 

 diff'er in so fundamental an aspect. In any case, whether these are parts 

 of the dendrites or extra-dendritic material, the dendrites, either by branch- 

 ing or by expanding to fill the lumen present a rather large part of their 

 surface to the outside. 



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