3 8 THE HAUNTS OF LIFE 



sponge body to a city like Venice, which is 

 traversed by canals, bringing in food and use- 

 ful materials, and carrying away waste. For the 

 sponge's body is traversed by inhalant canals, 

 bringing in food and oxygen (both carried by 

 the water), and bearing out useless particles 

 and waste products. The water, as we have 

 said, passes in by minute pin-prick holes all 

 over the surface of the sponge ; it passes out by 

 the large openings often about the diameter of 

 a lead-pencil. If a glass tube be carefully fitted 

 into one of these exhalant apertures, and one 

 need not be afraid of hurting the sponge, the 

 water will be forced up into the tube above 

 the level of the surface of the pool. Where 

 does the force come from? The pressure is 

 due to the ceaseless activity of lash-bearing or 

 flagellate cells, situated in chambers at the 

 junction of the inhalant and exhalant canals. 

 On their lashing the whole life of the sponge 

 depends. Does it not work hard for its living? 

 The sea-anemones nestling in the niches of 

 the rocks, some of them like chrysanthemums 

 when spread out, how do they get their food? 

 They wait for creatures, e.g. small crustaceans, 

 to touch their expanded tentacles, which are 

 covered with explosive stinging-cells and 



