COMPOSITION OF THE SPONGE. 125 



^we examine a drop of this liquid by the microscope, it would 

 ^appear entirely composed of very small transparent grains, 

 nearly of the same size, with some moisture. This jelly mat- 

 ter connects the different parts of the framework of the 

 •sponge, and lines the various canals or passages. The pores, 

 or apertures for perspiration, are minute openings on the 

 surface, protected by the framework, and into which the 

 water enters in currents, and after traversing the interior 

 passages, is ejected by means of openings which are larger 

 than the pores, and in many species are elevated above the 

 surface. To examine closely the framework or skeleton of 

 the sponge, it is necessary to macerate it in hot water, which 

 removes the gelatinous matter, and leaves it in a condition 

 to be examined by the microscope. This framcAvork con- 

 sists principally of two materials, one animal, the other min- 

 eral ; the first of a thready, horny, elastic nature ; the second 

 (the species most commonly used for domestic purposes) of 

 a flinty or chalk material. The thready portion consists of a 

 light pale-colored network, with some few exceptions always 

 solid, and varying considerably in size. The mineral por- 

 tion has little spines, which, if examined with the microscope, 

 show traces of a central cavity or canal, the extremities of 

 which are closed. 



How the growth and increase of the sponge is effected 

 affords matter of the deepest interest, and this, like every- 

 thing else in nature, shows the unerring wisdom of an all- 

 sustaining Providence. 



From the framework or skeleton of the sponge emerge, at 

 ■certain seasons of the year, a yellow kind of grain, which 

 projects as it increases in size into the cavities of the sponge, 

 and forms the germ or seed of another race ; these are egg- 

 like in appearance ; and a large portion of its surface be- 

 comes covered with little hairs, called eyelashes from their 

 resemblance to such. These hairs act as oars to the little 

 germ, to convey it away as soon as it falls on the water to 



