Langdon, Sense-organs of Nereis virens. 6g 



that of the above cells with the lens." Zernecke ('95) has fig- 

 ured and described in the subcuticular region of Ligula cells 

 from whose narrowed peripheral ends a number of fine processes 

 pass into the cuticula without any definite canals and some- 

 times, though not always, end under an insinking from the ex- 

 terior ; from the basal end of each cell one or two processes are 

 given off which never appear to be connected with nerves. 

 Zernecke calls these cells "Korbchen-zellen " and says they 

 " stehen vielleicht im Dienste der Nahrungsaufahme. " It 

 seems to me not impossible that both the "attenuated cells" 

 of Eunice and the " Korbchenzellen " of Ligula may be an- 

 choring cells for the attachment of muscles to the cuticula. If 

 this proves true, the insinking sometimes seem in the cuticula of 

 Ligula over one of these cells, will probably be found to be 

 due to a contraction of these cells and their muscles — a con- 

 traction due to the influence of reagents and strong enough to 

 tear the peripheral processes of the cells and the cuticula to 

 which they are attached away from the surrounding cuticula. 

 Summary. 

 /. T/ie Diffuse Sense- Organs. 



1 . The epidermis of Nereis virens contains a peripheral 

 sensory system composed of bipolar nerve-cells, which, except 

 for some doubtful cases in the parapodial cirri, are always 

 grouped into definite sense-organs. 



2. The bodies of the cells in these sense-organs, in all 

 regions of the body, are always situated in the epidermis itself. 



3. From the peripheral end of each sense-organ a bun- 

 dle of nerve-fibers — the peripheral processes of the nerve-cells 

 — passes to the cuticula and into a differentiated area in the latter 

 — an area composed of a deep inner and a shallow outer cavity 

 separated by a perforated membrane of cuticula. In the inner 

 cuticular cavity some of the peripheral processes branch. Each 

 finally terminates in a sensory hair. All of the sense-hairs 

 from a single organ pass to the exterior by means of the canals 

 in the perforated membrane belonging to the organ in question 

 and are, therefore, in direct communication with the external 

 world. 



