THE EVIDENCE OE THE AUDITORY APPARATUS 





time, my preparations are not sufficiently clear to enable me to 

 trace out the connections of these cells, especially their connections 

 with the special sense- 



organs. 



In Fi« 148 I 



give 



magnified representation 

 of a section through three 

 of these fiabellar sense- 

 organs. As is seen, the 

 section divides itself into 

 four zones : (1) the chi- 

 tinous layer (ch.) ; (2) 

 the layer of pigment (p.) 

 and hypodermal cells ; 

 (3) the layer of ganglion- 

 cells (gl); and (4) the 

 layer of nerve fibres (n.) 

 and blood-spaces (bl.). 

 The chitinous layer is 

 composed of the usual 

 three zones of the Li- 

 mulus surface — exter- 

 nally (Fig. 148), a thin 

 homogeneous layer, fol- 

 lowed by a thick layer 

 of chitin (3), in which 

 the fine vertical tubules 

 or canaliculi are well 

 marked ; the external 

 portion (2) of this layer 

 is differentiated from the 

 rest by the presence of 

 well-marked horizontal 

 layers in addition to the 

 canaliculi. 



In this chitinous layer 



r 



ch 



V 



cap 



can 



clv.t 



. 



mmm w 



m U ... 



: 9 ;*#» 



X 



<§\- 





Fig. 148. — Sectiok through theek Sbnse- 

 Organs op Flabellum. 



bl, blood-spaces; n., nerve; gl, layer of ganglion- 

 cells; p., pigment layer; ch., 1, 2, 3, the three 

 layers of chitin ; ch.t., chitinous tubule in large 

 tube of sense-organ ; cap., capitellum or swollen 

 extremity of large tube; can., very fine porous 

 canals or canaliculi of chitin. 



the special sense-organs 



are found. They consist of a large tube which passes through all the 



layers of the chitin except the thin homogeneous most external layer. 



