TOILERS IN THE SEA. 



unchanged. When this sediment is washed and 

 transferred to an ordinary slip of glass and viewed 

 under the microscope, it will be seen to consist 

 entirely of little transparent fragments of flint, re- 

 sembling glass, of regular and symmetrical form, 

 sometimes very beautiful, largely intermixed with 



FIG. l6. SPONGE SPICULES. . 



simple, straight, or curved bodies like needles and 

 pins. These are the sponge spicules, each form 

 having its own peculiar name, which is sometimes 

 very peculiar and very composite, intended to indi- 

 cate the particular form of "spicule." Dr. Bower- 

 bank has enumerated somewhere about two hundred 

 of these forms, but it would avail nothing to go over 



