Miscellaneous. 307 



localized in certain organs. The whole of my observations have 

 been made upon specimens of Asterias glacialis which have been 

 kept for a year in the aquarium of the Arago laboratory. 



(1) a. An Asterias having been isolated in a perfectly clean tub, 

 we wait until it is quite motionless and its ambulacral tentacles, 

 which are of no use for locomotion, near the oculiform spot, 

 retracted ; we shall designate these tentacles palps. When this 

 condition of perfect immobility has lasted for some time we place a 

 dead fish at about 50 centimetres from the Asterias. After a very 

 short interval (thirty seconds to one minute) the palps nearest 

 to the fish straighten out and the extremity of the arm carrying 

 them is raised ; this is the first indication that the Starfish has 

 detected the presence of the bait. Precisely the same movements 

 take place at the extremity of the other arms, and we then see the 

 stimulus starting from the extremity, communicating itself by 

 degrees to the ambulacral tentacles surrounding the mouth. The 

 Starfish begins to move towards the fish. Some individuals go 

 straight towards the bait, others hesitate a few moments. When 

 the Starfish is on the point of seizing the fish I remove it and place 

 it at a short distance from the arm which is posterior with reference 

 to the direction in which the animal is travelling. Carried away by 

 the motion which it has acquired, the Starfish then appears to 

 avoid the bait ; but its action soon changes, and we see it retracing 

 its path towards the new centre of attraction. In this way, for a 

 certain time, we can attract some individuals in all directions ; but 

 at length the animal becomes so much excited that it is incapable of 

 directing itself with certainty. 



b. Precisely the same phenomena are observed when we present 

 a living fish to the Asterias ; and if we suspend this fish at the 

 distance of the length of the arms of the Starfish from the bottom of 

 the vessel, the Starfish succeeds in seizing it : it rolls one of its arms 

 round the fish, and, hauling on this, it raises itself and applies its 

 mouth to its prey. 



We are therefore led to conclude, from careful observation of an 

 Asterias excited by a bait, that the sensations which it obeys are 

 felt by the extremity of its arms, at which point a delicate sensi- 

 bility was long ago declared to exist. Is the animal guided by sight 

 when it advances towards its prey ? The following experiments will 

 furnish the answer. 



(2) c. I removed the eye-spots from four of the arms of an 

 Asterias, leaving the adjoining palps as far as possible untouched : 

 and I saw this Asterias advance towards its prey with precision, 

 but in such a way that its single intact arm pointed in the opposite 

 direction to that in which the animal was moving. 



d. A tub is divided into two compartments by means of a board 

 placed at about 3 millimetres from the bottom. In one of the 

 compartments I place an Asterias, and when it is perfectly motion- 

 less I place in the other division a dead fish. I then cause a gentle 

 current of water to flow from the fish towards the division in which 

 the Starfish is ; the latter immediately manifests the peculiar excite- 

 ment noticed in observation a. It extends its palps and commences 



