588 THE MERMAID'S GLOVE. 



The true living being which constitutes the Sponge is of a soft and almost gelatinous 

 texture, to the unaided eye; and with the aid of the microscope is found to consist of an 

 aggregation of separate bodies like those of the Amoeba?, some of which are furnished with long 

 cilia. By the constant action of the cilia a current of water is kept up, causing the liquid to 

 enter at the innumerable pores with which the surface is pierced, and to be expelled through the 

 larger orifices. A Sponge in full action is a wonderful sight : the cilia drives the water in 

 ceaseless torrents, whirling along all kinds of solid particles, arresting those which are useful 

 for digestion, and rejecting those which it cannot assimilate. 



The reader will at once see that a creature thus composed will stand in need of some 

 solid framework on which the delicate fabric can be supported ; and on examining a. series of 

 Sponges with the microscope, we find that it is mostly composed of a fibrous and rather horny 

 network, strengthened with spicuke of a hard mineral substance. The shape of the spicula? is 

 extremely variable, some being simple translucent bars, some looking much like rough Hints ren- 

 dered transparent, others star-shaped with several points, while the greater number resemble 

 knotted clubs made of differently-colored glass, and having a lovely effect under the microscope. 



In the genus Grantia, which is well known to marine zoologists as having furnished 

 valuable information resiiecting the nutriment and reproduction of the Sponges, no horny 

 network can be found, but its place is supplied by the singular form of the spicuke, which 

 are composed of three long-pointed spines arranged so as to form a star of three rays. 

 These rays, on account of their shape, form an entangled mass, and answer the purpose 

 of the ordinary horny framework. A new species, termed Halichondria palmata, inhabits 

 the East Indies. 



There are several European species of the genus Grantia. Some of them are hollow, and 

 stand out with tolerable boldness from the objects on which they are set, while others are 

 always found as whitish incrustations upon stones and other massive substances. Their 

 structure is tolerably firm, and, on account of the absence of the horny framework, is not so 

 elastic as are the generality of the Sponge tribe ; and the texture is very close, but still porous. 

 1 With a microscope of tolerably high power, magnifying from two to three hundred diameters, 

 the layer of spicula? can be readily made out, interlacing with each other in wonderful pro- 

 fusion, and so completely intermixed that a single spicula is scarcely ever separable from the 

 general mass. 



The shape of the species belonging to this genus is extremely variable, but in all the 

 structure is remarkably simple, the wall being extremely thin, so that the ramifying canals 

 are not needed, and the water is merely absorbed through the minute pores of the wall 

 and expelled through the large orifice which forms the mouth of the sac. If the spiculse of this 

 or other Sponges be wanted in a separate state, the animal matter can be removed by heat ; 

 but a better, though slower process, is to immerse the speehuen in strong nitric acid or liquor 

 potassse, according to the flinty or chalky nature of the spicules. When separated they may 

 be mounted in two ways, namely, as dry and opaque objects, or in Canada balsam. 



We must now briefly examine a- rather important genus of Sponges, which has many 

 representatives. It is a very extensive genus, and its members are variously shaped, all, 

 however, agreeing in those salient points on which the group has been founded. They are all 

 spongy, elastic, not slimy, and with a very porous surface. 



One species is generally called the Mermaid's Glove, because it is apt to spread into a 

 form that bears a somewhat remote resemblance to a glove with extended fingers. It is cer- 

 tainly the largest of the European Sponges, sometimes attaining a height of two feet, and 

 stretching out its branches boldly into the sea. The branches are rather flattened, and when 

 full-grown are about an inch in width. They do not always remain separated throughout 

 their whole extent, but are apt to coalesce in various parts, and sometimes to form rudely- 

 shaped arches. 



The color of this Sponge is generally of a pale straw-yellow, and to the touch its exterior 

 is decidedly rough, on account of the myriads of spicula? which slightly project from the 

 surface. These spiculpe are needle-like, sometimes slightly curved and sometimes straight. 

 Mostly they are pointed at both ends, but as they are fragile and snap asunder with the least 



