42 HIDDEN BEAUTIES OF NATURE 



the Australian varieties these spikes are so fine that 

 his hand was pierced with them before he was aware 

 he had approached so closely to them. Some spikes 

 are club-shaped, while others are three-sided. 



As regards the pedicellarise, they are not separate 

 individuals, but form essential parts of the sea-urchin. 

 Miiller, the famous Danish zoologist, thought they 

 were parasitic animals. This is not to be wondered 

 at, for there are few more mysterious organisms in 

 that portion of marine life which is known to zoolo- 

 gists. To this day there is considerable doubt as to 

 the services they render to the urchin. It consists of 

 a fleshy stem, perforated by a calcareous shaft, which 

 rests on the skin of the creature, and of a head which 

 has three divisions, and which bears close resem- 

 blance to the head of a bird. The edges of these 

 pieces, which open and shut, are provided with teeth. 

 The whole structure is clothed with transparent flesh, 

 and the head, besides opening and shutting, can 

 move to either side. All the movements seem to be 

 voluntary. These supposed voluntary motions must 

 have caused Miiller to believe them to be separate 

 creatures parasitic upon the echinus. Their minute 

 structural details are marvellous. When alive, the 

 action of the pedicellariae creates great amusement. 

 They are charming objects for microscopical exami- 

 nation, and as their duties are not fully known, they 

 arouse the interest of all who observe them. The 

 late P. H. Gosse, F.R.S., suggested ' that they are 

 intended to seize minute animals, and to hold them 



