THE LIVING STRUCTURES 119 



Crinoid. It cannot move, it has no eyes ; it makes no at- 

 tack; it does no harm. It simply eats, playing the part of 

 universal scavenger of the seas, catching all foods that 

 fall through the waters, animal and vegetable, in its ten 

 or more waving arms, each of which has a long groove 

 lined with propulsive hairs that work the food along in 

 the manner of a moving stairway to a central mouth and 

 stomach. This stomach lies between the basis of the 

 arms, which rest either upon a long stalk or upon two or 

 three dozen legs, that cling fast to rocks or other animals 

 or spread out upon the surface of the mud. The crinoid 

 is perhaps the only creature in the sea that is not desired 

 as food by some other creature, but these animal lilies, 

 which eat everything, are not themselves to be eaten, be- 

 ing too brittle, too full of lime, all skeleton, as it were. 

 Even the stomach of a crinoid has its own skeleton." 



You will notice that this animal is just as much a plant 

 as an animal. There is no difference in the beginning nor 

 in the development of a plant or animal. It is put up for 

 a purpose. If it is to be a stationary structure, it will look 

 like a plant ; if it is to be a movable structure it will look 

 like an animal. It all depends upon the purpose for which 

 it is made. This animal, which grows like a plant in the 

 bottom of the sea, is merely a house lit up with phos- 

 phorescent lights wherein dwell millions of individual 

 cells. 



We might next consider a very large group of struc- 

 tures known as shell animals. The cells live in a social 

 colony which is protected with a shell made of lime and 

 other material. The shells that protect them are usually 

 of such strength and thickness as would be required to 

 withstand the pressure and force of the water at that par- 

 ticular place, or the animals that may attack them. They 

 are simply movable houses wherein live vast colonies of 



