500 NATURAL HISTORY OF HAWAII. 



the reefs have any great commercial value, it is uot improbable that the fine 

 soft species of commerce, suited to our climate and conditions, could be intro- 

 duced and grown here. 



Anyone who sees the living sponge will realize that the familiar bath 

 sponge is only the bleached skeleton of the animal from which all of the soft 

 part has been macerated and washed away, leaving onh- a substance known as 

 spongin — a substance very like silk in its composition. 



The division of the sponges is made not on color or shape nor habits, but 

 on the differences in their skeletons. Two principal classes are recognized : 

 one where the skeleton is composed of limy spicules ^^ ; the other class includes 

 species with glassy ■^^ spicules or Avith horny ^- fibers. To the non-calcarious 

 class belong the majority of the larger sponges on the Hawaiian reefs. 



Seaweed. 



It is a very natural transition in this connection to pass from the curious 

 sponge animals, that so often resemble plants, to the consideration of the 

 flora of the coral reef, since these curious marine representatives of the vege- 

 table and animal kingdoms occur together, often in the most intimate relation, 

 about our shores. In fact, many of the species of seaweed are attached to 

 various species of sponges, and even more frequently sponges will be found 

 growing on the larger forms of algfe. 



The examination of the heaps of curious bright-green, browii, purple or 

 red plants cast ashore by the sea, particularly after a heavy storm, gives to 

 the beach ramble a charm in any quarter of the globe, but in Hawaii, with its 

 hundreds of miles of ever-varying coast line, the gathering of the sea-mosses holds 

 out allurements to the lover of the beautiful in nature that few can long resist. 



How TO Collect Hawadax Alg.e. 



To gather and preserve these bright-colored flowerless plants is so easy 

 and so fascinating a task that tourists who visit the islands, as well as old 

 and young people who call Hawaii home, can find no more pleasant diversion 

 than making a collection of the more common forms. 



The first step in reef collecting of any kind is to find out the time each 

 day when the tide will l)e low and arrange to be on the reef two or three hours 

 before extreme low water, so that the tide may be follow^ed out. However, 

 algjB hunting, as well as reef collecting generally, may be greatly facilitated if 

 the collector can have the use of a boat, a fine-toothed long-handled rake and a 

 w^ater box with a glass bottom. Still more ambitious collectors will want to 

 use a dredge, though dredging about a coral reef is very difficult work. Those 

 who are not able to dredge or wade, will find the sea-coast at high tide fur- 

 nishes specimens of most of the species to be gathered first-hand farther out. 



The collector will want a light canvas bag, or wicker basket, and a small 



3" Calcarea. *" Xon-Ciilrnrin. *' Silicioiis. ■*" Spongin. 



