532 THE POPULAR SCIENCE MONTHLY. 



through the living mass, the sarcode obtains its nourishment, and the 

 skeleton its growth by a sort of absorption, or what is known to the 

 physiologist as endosmotic action of the cells. We have then men- 

 tioned above three clearly specialized functions, as represented respec- 

 tively by the inhalant pores, the exhalant oscula, and the uniciliated 

 cells. And it is certainly a matter of prime importance that each cell 

 should have this single lash. In fact, it raises it to the rank of a pacha 

 with one tail, in a community where all are pachas of this dignity, and 

 each one a commissioner of the water department, and a commissary 

 of subsistence. " Both the oscula and pores can be closed at the will 

 of the animal ; but the oscula are permanent apertures ; whereas, the 

 pores are not constant, but can be formed afresh whenever and wher- 

 ever required." 



The sponges are the active eliminators of the salts of the ocean. 

 In a large laboratory certain substances are kept in solution, so as to 

 be ready to the chemist's hands. Nature's grand laboratory is the sea. 

 There her little economic chemists are ceaselessly busy extracting, and 

 putting into solid forms, the various mineral substances held in solu- 

 tion. Thus the coral polyps eliminate the carbonate of lime with 

 which to build their beautiful structures. And the Alcyonarian polyp 

 in this way builds up the delicate sea-fan, with its skeleton of keratose, 

 or horn-like substance. And so is it with the sponges. They, too, are 

 elaborators of the mineral treasures of the sea. Hence it has been at- 

 tempted to group them upon considerations of their special building 

 propensities. In this way the toilet-sponges, and, in general, those of 

 commerce, which all affect horn, or keratose, in the structure of their 

 skeletons, woidd be grouped together as the Keratosa ; while those 

 which choose lime would be called Calcarea ; and those which build 

 up with silex would be known as the Silicea. We have mentioned 

 these groups in their order of rank. The highest is the vitreous, or 

 glass-sponge, with which we are directly concerned. 



In the recent deep-sea dredging, so charmingly described in Dr. 

 Wyville Thompson's new book, " The Depths of the Sea," an account is 

 given of the obtaining in British waters, at the depth of 30,000 feet (!), 

 specimens of the Hyalonema, the famous Glass-Rope Sponge. It had 

 been previously obtained from the coasts of Portugal, wdien the news 

 astonished naturalists, as previously it had only been known as coming 

 from Japan. It is, indeed, a wonderful object. We once saw a speci- 

 men in the cabinet of a learned institution. The professor pronounced 

 it a coil of Japanese spun glass. " No," said another savant, " it is a 

 plant." And at that time both were excusable, for even Ehrenberg had 

 looked upon it as " an artificial product of Japanese industry." That 

 is to say, the great microscopist regarded the object as an ingenious 

 imposition, consisting of natural products artfully put together. Let the 

 reader carefully inspect the cut of Hyalonema, Fig. 1, which we have 

 taken from Dr. Thompson's book, and then let us attempt a description. 



