SPONGB 13 



gins ; the smaller are much more minute, running in all 

 directions, and constituting what are termed the pores of 

 the sponge. 



Fig. 1. 



10. The structure of the living sponge is shown by 

 Fig. 1, where it will be observed that the larger orifices 

 are much more conspicuous than in the dead one, these 

 elevated parts being usually almost obliterated by the 

 death of the animal, and by pressure in packing it for 

 market. 



11. From these orifices, Dr. Grant has discovered that 

 in the living sponge there is a constant stream of the fluid 

 in which the animal is immersed. A small piece of liv- 

 ing sponge being placed in a watch-crystal filled with 

 sea-water, and the whole placed under a microscope, 

 Dr. Grant perceived some motion among the opaque 

 particles of the fluid. " On moving the watch-glass," 

 says he, " so as to bring one of the orifices on the side of 

 the sponge fully into view, I beheld, for the first time, 

 the splendid spectacle of this living fountain, vomiting 

 forth, from a circular cavity, an impetuous torrent of 

 liquid matter, and hurling along, in rapid succession, 

 opaque masses, which were strewed everywhere around. 

 The beauty and novelty of such a scene, in the animal 

 kingdom, long arrested my attention, but after twenty- 

 five minutes of constant observation, I was obliged to 

 withdraw my eye from fatigue, without having seen the 

 torrent for one instant change its direction, or diminish, 

 in the slightest degree, the rapidity of its course. I con- 



What was the experiment by which Dr. Grant proved that sponge is ail 



