228 ORGANS OF SENSE 



sometimes the presence of air renders them very con- 

 spicuous, they are in others by no means easy to make 



Fig. 7. 



Diagrammatic section through part of Fig. 6. 



c, chitinou.s skin of the antenna, e e, two of the cork-shaped 

 organs, s, external chamber of one of the stethoscope-shaped 

 organs, t, the tube. 7V, the posterior sac. 7i, the nerve. 



out ; and I think that when a small number only are 

 apparently present, this is probably due merely to the 

 fact that the others are not brought out by the mode 

 of preparation. 



In addition to the group of these organs situated 

 in the terminal segment, there is one, or in some rare 

 cases I have found two, in each of the small preceding 

 segments. The tubes in these segments appeared to 

 the eye to be nearly of the same length as those in the 

 terminal segment, but I could not measure their exact 

 length, as they do not lie flat. In some cases, when 

 the segment was short, the tube was bent — an indica- 

 tion, perhaps, that the exact length is of importance. 

 It is possible that these curious organs may be audi- 

 tory, and serve like microscopic stethoscopes. Professor 

 Tyndall, who was good enough to examine them with 

 me, concurred in the opinion that this was very pro- 

 bable. I believe I am correct in saying that the bend- 



