18 



TACTILE HAIRS. 



The tactile hairs — as, for instance, those on the upper 

 side of the proboscis of the fly — are delicate, hollow, 

 tapering, pointed organs, inserted on a chitinous ring, 

 and connected with a nerve which immediately below 

 the skin swells into a multicellular ganglion. 



Fig. 20.— Right half of eighth segment of the body of the larva of a gnat (Coi-eihra 

 plumicornis) ; after Graber. E, G, Ganglion ; N, nerve ; g, auditory ganglion ; 

 gb, auditory ligament ; (Jh, auditory rods ; a, auditory nerve ; e, attachment of 

 auditory organ to the skin ; b, attachment of auditory ligament ; hn, hn', termi- 

 nation of sliin-nerve; tb, plumose tactile hair; h, simple hair; tg, ganglion of 

 tactile hair ; hn, longitudinal muscle. 



The terminations of the nerves and their connection 

 with the sensitive hairs are also beautifully shown in 

 some of the transparent water-insects. Fig. 20 repre- 

 sents part of one segment of the glassy larva of a gnat 

 {Gorethra flumicornis), showing the tactile hairs (Fig. 

 20, hj th), and the nerves connecting them with the 

 central ganglion (Fig. 20, EG). 



