STAR- FISH AND SEA-URCHINS. 321 



On removing with a pointed scalpel the eye-spots 

 from a nunber of Star-fish and Echini, without 

 othervvise injuring t1ie animals, the latter no longer 

 crawled towards the liifht, even thouo^h this were 

 admitted to the tink in abundance; but they 

 crawled promiscuously in all directions. On the 

 other hand, if only one oat of the five eye-spots were 

 left intact, the animals crawled towards the light 

 as before. It may be added that single detached 

 rays of Star-fish and fifth-part segments of Echini 

 crawl towards the light in the same manner as 

 entire animals, provided, of course, that the eye-spot 

 is not injured. 



The presence of a sense of smell in Star-fish was 

 proved by keeping some of these animals for several 

 days in a tank without food, and then presenting 

 them with small pieces of shell-fish. The Star-fish 

 immediately perceived the proximity of food, as 

 shown by their immediately crawling towards it. 

 Moreover, if a small piece of the food were held in 

 a pair of forceps and gently withdrawn as the Star- 

 fish approached it, the Minimal could be led about 

 the floor of the tank in any direction, just as a 

 hungry dog could be led about by continually 

 withdrawing from his nose a piece of meat as he 

 continually follows it up. This experiment, how- 

 ever, was only successful with Star-fish which had 

 been kept fasting for several days ; freshly caught 

 Star-fish were not nearly so keen in their manifesta- 

 tions, and indeed in many cases did not notice the 

 food at all. 



Desiring to ascertain whether the sense of smell 



