180 THE MICROSCOPE. 



carbonic-acid gas, should be generally admitted to constitute tbe true 

 line of demarcation between the two, and would thus remove the ob- 

 jections raised by those who will not admit the presence of starch as 

 sufficient to determine the point. Professor Grant has more recently 

 examined the sponges ; and from his patient and careful observations 

 of them, they have been finally classed amongst the animal creation. 

 He ascertained that the water was perpetually sucked into the substance 

 of the sponge through the minute pores that cover its surface, and again 

 expelled through the larger orifices. His own account is so very inter- 

 esting, that we cannot resist giving, in his own words, the results 

 arrived at in these investigations: "Having placed a portion of live 

 sponge {Spongia eoalita, fig. 102, No. 1) in a watch-glass with some sea- 

 water, I beheld for the first time the splendid spectacle of this living 



fig. 102. 1, Spongia eoalita. 2. A piece of ySpoa^ia^awicea highly magnified. ' 



fountain, represented in fig. 102, No. 2, vomiting forth from a circular 

 cavity an impetuous torrent of liquid matter, and hurling along in rapid 

 succession opaque masses, which it strewed every where 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 the rapidity of 

 its course. In observing another species {Spongia panicm), I placed 

 two entire portions of this together in a glass of sea-water, witb their 

 orifices opposite to each other at the distance of two inches; they 

 appeared to the naked eye like two living batteries, and soon covered 

 each other with the materials they ejected. I placed one of them in a 

 shallow vessel, and just covered its surface and highest orifice with 



