THE NERVE-NET 121 



piece of crab meat or fish flesh is brought into contact with 

 a tentacle, it adheres firmly to the tentacle which quickly 

 shortens and is usually covered by several adjacent ten- 

 tacles. The piece of flesh is thus held on the oral disc 

 of the animal, which contracts in such a way as to move 

 the mouth gradually toward the food till this aperture 

 is near enough to swallow the- flesh. The animal then 

 slowly returns to a state of quiescent expansion. 



When a tentacle of Condylactis is cut off and allowed 

 to float in seawater, it contracts to about one-third its 

 former length and remains almost indefinitely in this 

 condition. Relaxation apparently never fully returns. 

 If such a tentacle is caught on its cut edge by a delicate 

 metal hook, it may be held with its open basal end at the 

 surface of the seawater and inflated by gently running 

 seawater into it. In this way a severed tentacle may be 

 made to expand to about two-thirds its normal length 

 and, under these circumstances, it will exhibit just about 

 that degree of distension and mobility as is seen in the 

 attached tentacles. If now, more seawater is discharged 

 into it, it is likely to elongate a little and then contract 

 considerably, discharging much of its contained water. 

 Obviously for experimental purposes the fairly distended 

 tentacle offers the most favorable condition. 



Tentacles suspended in seawater and expanded to 

 about two-thirds their natural length remain quiescent 

 for considerable periods. From time to time, however, 

 they show spontaneous movements consisting of slight 

 contractions and twistings by which more or less of their 

 contained fluid is discharged. If this is replaced, they will 

 reexpand and thus periods of quiescence are followed by 

 periods of activity. In these respects the severed ten- 



