WORMS AND POLYZOA 8 1 



broad. The tube is bent into a U and in this resides a 

 four-inch long worm of remarkable form. It has a funnel- 

 shaped head provided with two tentacles and a pair of eyes, 

 nine pairs of lobe-shaped feet and a number of club-shaped 

 segments terminating in feet which anchor the worm to 

 its retreat. The club-shaped segments keep up a rhythmic 

 pumping motion which causes a steady current of water 

 to flow through the tube, aerating the worm's blood 

 and at the same time bringing food to it. The worm 

 is highly phosphorescent and any disturbance in the water 

 intensifies the greenish glow given out of every part of 

 the animal. Of what service this can be to the worm 

 no one has yet offered a satisfactory explanation. The 

 light causes a very obvious halo over the mouth or burrow 

 and advertises the worm's presence to its undoing, for 

 many fish automatically make for the light and either 

 drag out the worm or devour it with tube complete. 



The Leeches, so abundant in all fresh waters, are in 

 our own seas represented by only two species. Like their 

 fresh-water relations they are more or less parasitic, 

 chiefly attacking fish. 



The Polyzoa — -multiple animals — are so named from 

 the fact that they live in large colonies like corals. For 

 many years biologists the world over have been endeavour- 

 ing to arrange all animals in an orderly sequence, but there 

 are certain forms which seem to have affinities with widely 

 separate groups, and the Polyzoa fall into this category. 



To the average man they suggest plants, but the biologist 

 knows them to be comparatively highly-organised animals 

 with a definite gut and body cavity. The bulk of the 



