130 RAMBLES AND REVERIES. 



These creatures are as much higher in the scale 

 of organisation than rotifers as rotifers are above 

 amoebse. They are placed by zoologists amongst what 

 are called Polyzoa, a word which means " many 

 animals." Polyzoa constitute the lowest division of 

 Mollusca, so that, in fact, they are poor relations 

 of the snail, the oyster, and the cuttle-fish. They 

 chiefly inhabit salt water, and one of the most 

 familiar of the Polyzoa must have been seen by every 

 visitor to the seaside, though perhaps by the majority 

 regarded as a piece of decaying seaweed. This is the 

 sea-mat, or Flustra, which lies about everywhere on 

 the seashore. When looked at with the naked eye, 

 it is exactly like a piece of whitish-brown seaweed. 

 But pick it up and examine it with a pocket lens, 

 and you will see a vast number of lovely crystalline 

 cells, all built up according to the same pattern. If 

 you can dredge up a living specimen, and will place 

 it at once in water, you will see very soon a beautiful 

 sight. Out of these cells will rise multitudes of 

 ciliated tentacles, which wave and rotate in the 

 water in a remarkable way. There is another sea- 

 side polyzoon almost as common as the flustra, and 

 this assumes the form of a miniature fir-tree, for 

 which reason it is called the sea-fir, or S&rtularia. 



There are, however, many fresh-water species of 

 Polyzoa, of which one of the commonest is Pluma- 

 tdla repens. Let us suppose we are looking at this 

 through the half-inch objective, with the light shin- 

 ing through it from beneath in a somewhat oblique 

 direction, in order not to alarm the timid creatures, 

 and also to enable us to get a better view of the cilia. 



