264 AN HOUR AMONG THE TORBAY SPONGES. 



animal life, spontaneous movement of parts, and 

 sensibility to touch. 



The thoughtful observer, watching the evolution of 

 this unintermitted current, ever pouring out with such 

 power and velocity and volume, would ask, What is 

 the nature of the force that vomits forth the fluid ? 

 what its seat ? and whence the supply ? No visible 

 current passes inward from without ; still, as the 

 stream is continuous, and yet the quantity of water in 

 the ceh 1 does not increase, it is manifest that the water 

 from without must enter in the very same ratio as it 

 is expelled. In order to understand this, we must 

 cut or tear a Sponge to pieces. We shall find that 

 the round apertures are the mouths of a few large 

 canals which run through the interior ; that into 

 these open, at irregular intervals, other subordinate 

 canals ; that these receive others smaller still ; these, 

 again, others, in an ever-diminishing ratio ; till at 

 last we can no longer trace them as canals, the whole 

 superficial portion of the Sponge being pierced with 

 microscopically minute and innumerable pores. Into 

 these the external water is constantly being absorbed, 

 carrying with it both oxygen for respiration, and 

 organic matter for nutrition. The influent water, 

 parting with these elements, and thus revivifying the 

 living gelatinous flesh that clothes every fibre, gra- 

 dually permeates the whole interior, flowing along 

 the pipes in succession, till at length it gathers into 

 the larger canals, and is poured out at their apertures, 

 as we have seen ; just as the waste water from every 



