THE GLASS-SPONGES. 



533 



Suppose we should take a skein of smooth, compactly-spun, glossy- 

 white silk, about twenty-four inches in length, and, cutting the ends 

 off evenly at one extremity, should give it a loose twist along the en- 

 tire length, except some six inches at the bottom, which we leave, so 

 to speak, frayed, or shaken out. Then around the other end of this 

 silken cord or coil we affix a cup-like tuft of buff-colored zephyr 

 worsted-work, having the end of the skein projecting a little higher 

 than the rim, and covered with the same material. Now, from just 

 below the base of the cup-like tuft, let us encase the white coil tightly 

 down to where its threads fray out ; let this cylindrical case be of a 

 dark-brown color, and leathery aspect, and ornamented with little 

 starry knobs or warts, like raised embroidery and then, so far as form 

 is concerned, you have the Hyalonema, or glass-sponge of Japan. 



It thus appears from the above that the structure has three parts 

 the buff-colored mass at one end, the long shaft of white threads, and 

 the star-embossed case which envelops the axis or shaft. Now, what 



Fig. 2. 



White. 



Red. 



White. 



Japanese Drawings of Hyalonema Sieboldi. (The artist, not knowing the facts in the case, 

 has figured them in wrong position. Compare with Figure 1.) 



is the material nature of each part ? There is no difficulty about the 

 buff-colored mass, in form like a cup. It has the spicules, and the 

 sarcode, which characterize the sponge-flesh. The axis or coil is of 

 pure translucent silex, like white threads of glass. The surrounding 

 sheath, with the starry prominences, is of a horny or keratose mate- 

 rial, much like the stems of the sea-fans, and it is a curious fact that 



