8EA URCHINS MATERIAL AND DEVELOPMENT. 81 



will go still further, and, by violently contracting the 

 body in several places, will actually cut itself into 

 pieces. 



The Synaptas exhibit a beautiful set of appendages to 

 the skin. They are, however, so minute that their forms 

 cannot be seen without the aid of a microscope. 



The skin is nearly covered with little tubercles, and 

 upon the tubercles are set a. number of transparent 

 spicules formed almost exactly like the anchors used by 

 the ancients. The shank of the anchor is affixed to a 

 little shield composed of the same material, which is 

 pierced with holes arranged so as to produce a definite 

 pattern. 



Each species of Synapta has its own pattern of anchor 

 and shield, so that a collection of them forms a singularly 

 interesting set of microscopic objects. 



The object of these tiny appendages is at present a 

 total mystery. Their very presence shows that they 

 must subserve some use, and the elaborate care with 

 which they are formed shows that the use must be an 

 important one. But Creation is so large, and man is so 

 small, that a nebula of the skies and a spicule of the 

 Synapta are equally beyond man's grasp, the one from 

 its immeasurable magnitude, and the other from its 

 extreme minuteness. 



