THE GLASS-SPONGES. 53 i 



In a word, what is the function of this lash in each of these cells, 

 which, combined, and taken with the skeleton, constitute a sponge ? 

 Let us try to see. If we take a morsel of a toilet-sponge, and put it 

 under a microscope of moderate power, we find that it is made up of a 

 mass of complicated net-work. There is more or less regularity in the 

 meshes; and these are found of various patterns in the different species. 

 This heap or mass of net-work, commonly called a sponge, is really 

 the skeleton of the sponge. When living it is covered with, or literal- 

 ly embedded in, a glairy, gelatinous, or albuminous substance. But 

 this is so unlike ordinary animal tissue for it seems, really, tissue- 

 less that it has received the technical name sarcode. This sarcode 

 fills the meshes above mentioned ; and is held in place by innumera- 

 ble tiny spicules, mixed in, so to speak, like the hair in the mortar of 

 the plasterer. So little consistency has this sarcode, or sponge-flesh, 

 that but for this natural felting it would dissolve and flow away. 

 Now, take an ordinary sponge into the hand. We observe several 

 large apertures, at or toward the top. These are called the oscula. 

 They are the exhalant vents of the entire system. At these openings 

 is expelled, with some force, the water that has been taken into the 

 living mass, and deprived of its nourishment. But how is the water 

 brought in through that glairy sarcode ? Besides the oscula, which 

 are few, and readily seen, even in the skeleton, there are innumerable 

 tiny inlets known as pores. These are not visible in the skeleton, 

 as they really belong to the sponge-flesh. These pores open into the 

 meshes, and enter directly certain little cavities, or chambers, that 

 stand connected with circuitous passages, which finally lead to the 

 large outlets, or oscula. The pores are very small, and yet, compared 

 with the cells, are very large. The little chamber into which the pore 

 opens has its walls built up with these uniciliated cells. Now, if we 

 could only peep into the privacy of that chamber, with its walls of 

 living stones, without making any disturbance, we should find every 

 cell lashing its cilium with great vigor, and all in such harmony of 

 accord, that it would seem like 



" Beating time, time, time, 

 In a sort of Runic rhyme." 



The beating of each lash is doubtless downward, that is, inward ; the 

 effect of which is, a vacuum above, into which the water presses 

 through the external pore. A second result of this downward beat- 

 ing of the cilia from a myriad of cells is, the impulsion of the passing 

 water through the ramifications leading to the oscula. Thus the run- 

 ning of the waters is the sponge's ancient " Runic rhyme." Every 

 sponge, then, has a very complete aquiferous system : its conduits at, 

 the entrance of and along which the busy one-lashed cells occupy 

 themselves forcing the water along ; and the oscula, which may be 

 likened to the outlets of sewers. During this circulation of the fluid 



