SPONGES. 33 



carried out through the oscula. Each of these cells may be 

 taken therefore as a separate individual, enjoying home rule, 

 yet taking part in general efforts for the whole sponge-com- 

 munity, for we find that by some strangely communicated 

 understanding, all these cells cease lashing the water for a 

 time as though resting (or digesting their food), and the 

 craters cease to pour forth their streams. But then after a 

 time activity is resumed, the craters belch forth again, and 

 we know thereby that the flagella are in active operation down 

 below, not merely capturing and digesting food, but also 

 absorbing oxygen from the inflowing streams, whereby vital 

 energy is maintained. 



After the cells have become full grown, they split trans- 

 versely or longitudinally, and so increase their number, which 

 means that the size of the colony increases. But some of 

 these divided portions develop into eggs, which after fertiliza- 

 tion are swept out into the ocean by the outflowing current, 

 and settling upon some rock become glued down and grow, 

 gradually, by division and subdivision, producing a new 

 colony. Such is a highly condensed account of the general 

 phenomena of sponge life. There are variations upon it in 

 the life-history of well-nigh every species ; but this will suffice 

 to give my reader a general idea of what sponges are. For 

 the rest, he must go down among the rocks, and search out 

 the various species of many forms, and endeavour to add to 

 the general sums of knowledge by some fresh observations 

 respecting British Sponges. 



However startling the statement may sound, there is no 

 lack either of specimens or species on the British coasts. 

 Some of the most conventionally sponge-like of these must be 

 sought by the dredge in deep waters, but our own hunting 

 ground, the rocks that mark the shoreward-bounds of the 

 laminarian zone, if carefully inspected at low spring tides, 

 will afford more specimens in half-an-hour than we can 

 exhaust the interest of ia a week. That this is no mere 



