NERVOUS SYSTEM OF THE TUNICATE 321 



3. The desiphonated bodies of the operated animals recover 

 sensitivity after the operation, live and regenerate new siphons. 



4. The ganglion is not necessary to the process of regeneration 

 of amputated siphons, as regeneration occurs even if the ganglion 

 be amputated with the siphon. A new ganglionic mass appears 

 in addition to the new siphon, 



b. With ganglion removed. 5. Extirpation of the ganglion has 

 two main effects : a) an interruption of coordination between the 

 siphons; b) a reduction of tone and general irritability of the 

 animal. 



6. The ganglion regenerates in from four to six weeks. 



7. Coordination is reestablished with regeneration ~ of the 

 ganglion, and irritabihty is restored to almost its original degree. 



8. The new ganglion is very quickly fatigued. 



C. Normal animal to chemical stimulation 



Lip-lobes, oral tentacles, and pharyngeal lining are sensitive 

 to solutions of HCl, NaCl 2n, NaOH n/10, but are insensitive 

 to 50 per cent cane-sugar solution. Quinine crystals applied to 

 the lip-lobes cause siphons to close; applied to the oral tentacles, 

 they cause these to flip up. 



D. Operated animal to chemical stimulation 



Quinine crystals applied to the lip-lobes or oral tentacles of 

 amputated siphons produce the same but less vigorous response 

 as for the normal animal. 



E. Normal animal to vibratory stimulation 



Both siphons are sensitive to disturbing vibrations in the 

 room. 



F. Operated animals to vibrations 



Amputated incurrent siphons respond only provided they are 

 cut off to include the circlet of tentacles; amputated excurrent 

 siphons are insensitive. Deganglionate animals respond with 

 closure of both siphons, but a more vigorous stimulation than 

 normal is needed to elicit the response. 



