132 MR. G. J. ROMANES ON THE 



them quickly and accurately to perceive the direction from which 

 the odour of food is coming, provided that the distance of such food 

 as I have named is not more than a few inches from the animal. 



"With the view of ascertaining whether or not this olfactory 

 sense is localized in the ocelli, I removed the latter from all 

 the rays of the same starfish with the point of a scapel, and 

 then repeated the experiment. The result was the same ; thus 

 showing that the ocelli are not specially concerned in the sense 

 of smell. Next I tried the effect of removing the whole tips 

 of the rays ; but still there was no change in the result of 

 the experiment. Nor was there any change produced when the 

 rays were progressively truncated further and further down : 

 the olfactory sense was found to be distributed throughout their 

 length. 



The question still remained whether this sense was equally 

 distributed on the upper and lower surfaces of the rays. I 

 therefore placed a piece of crab upon the upper surface of the 

 disk of another hungry starfish, and found that the animal 

 carried the food upon its back for any length of time without 

 seeking to remove it with its rays, as starfish seek to remove 

 from that position any source of irritation. I also tried the 

 experiment of varnishing the upper surface of a starfish and 

 placing food before its rays, with the same result as I obtained 

 with unvarnished specimens. It was not practicable — seeing that 

 it would have interfered with the action of the feet — to try the 

 converse experiment of varnishing the under surface while leaving 

 the upper surface unvarnished, or this w^ould have supplied a still 

 better test ; but I think that the experiments which were prac- 

 ticable are sufficient to show that the sense of smell is distributed 

 over the lower surface, while not extending to the upper surface. 

 In all these respects detached rays behave in the same way as 

 the entire animal ; but if in the entire animal the central nerve- 

 ring is divided between each of the rays, the animal ceases to 

 follow the food with precision, owing to the loss of coordination 

 between the rays which the operation has entailed. 



In the paper already referred to, evidence was adduced to 

 show that, at all events, one function of the pedicellari^e is that 

 of assisting locomotion by seizing fronds of sea-weed, and holding 

 them steady until the pedicels have time to gain attachment by 

 their adhesive disks. Some additional observations tending to 

 strengthen this evidence may here be stated. 



If an Echinus is allowed to form its adhesions either by its equa- 



