THE NERVOUS SYSTEM OP ANTEDON EOSACEUS. 277 



without the slightest disturbance or irritation of any kind, it began 

 spontaneously to swim again actively and normally. Coming in 

 contact with a piece of stick, it attached itself to it by the dorsal cirri, 

 and remained there for more than a week. 



The above experiment is the same as Dr. Carpenter's Experiment B 

 described above. It is extremely important as proving that the 

 co-ordinating mechanism which regulates the complex swimming 

 movements of the arms is entirely without the visceral mass. As the 

 direct connection between the subepithelial bands of the several arms 

 is also destroyed, the experiment renders it extremely doubtful whether 

 these bands have any part in regulating the swimming movements of 

 the arms. 



Experiment 2. — An active specimen was eviscerated, and allowed to 

 come to rest. The ventral surface of one of the arms was then 

 irritated gently with a needle; active movements both of the irritated 

 arm and of the others resulted. The same effect followed irritation of 

 one of the ordinary pinnules ; while irritation of the oral pinnules 

 caused immediate and strong flexion of all the ai'ms. 



This shows that the effect of irritation of the arms or pinnules is 

 practically unmodified by the removal of the visceral mass ; the only 

 difference I have noted being that the response is slightly quicker and 

 more extensive in an eviscerated than in an uninjured specimen. The 

 nervous connection between the sensory epithelium of any one of the 

 arms or pinnules and the muscular system, not only of that arm, but 

 of all the others as well, must, therefore, be without the visceral mass. 



As a source of irritation in this and other experiments I employed 

 at first scratching with a sharp needle. I found afterwards that nipping 

 with forceps was preferable, as the needle is apt to shake the whole 

 animal, and so cause disturbance of parts other than those it is desired 

 to irritate. The nip should be a sharp sudden one, and the irritated 

 part released at once. In all the experiments here recorded, except 

 when otherwise specified, both needle and forceps irritation were tried. 

 In some instances the application of acid by a fine brush was made use 

 of as an irritant; but this can only be done satisfactorily on specimens 

 removed from the water. 



Experiment 3. — An active specimen was eviscerated and allowed to 

 come to rest in the normal position. It was then inverted and placed 

 mouth downwards on the bottom of the tank. After a short rest it 

 righted itself in the normal manner, but rather more slowly than usual, 



