SENSE-HAIRS. 



17 



forated, and a special nerve-fibre runs to the base of the 

 hair. 



1. Hairs solid. 



(1) Hairs attached stiffly ; organs of touch 

 (Fig. 18, c). 



(2) Hairs attached by means of a thin mem- 



brane, sometimes plumose ; organs of hear- 

 ing (Fig. 18, d). _ 



2. Hairs hollow, and either open at the end, or 

 closed by an extremely delicate membrane. 



(1) Hairs containing a continuation of the 



nervous plasma; 

 organs of smell 

 (Fig. 18, e). 



(2) Hairs generally 

 very short, and 

 situated in the 

 mouth or on the 

 mouth part ; or- 

 gans of taste 

 (Fig. 18,/). 



Each of these classes 

 is again subject to end- 

 less modifications, and 

 others will doubtless here- 

 after be discovered. The 

 sense-hairs are also often 

 more or less completely 

 sunk in the chitinous in- 

 tegument. 



Fig. 19 shows some of 

 the tactile hairs on the proboscis of a fly (Musca), each 

 seated ^ a ganglion and connected with a nerve («). 



Fig. 19. — Part of the proboscis of a fly 

 (Musca); after Leydig. n. Nerve; g, 

 ganglionic swellings ; s, tactile hairs or 

 rods; c, cuticle. 



