THE ANIMAL KINGDOM. 



159 



appearance of pillars supporting several floors of a 

 building. 



Protozoa, or First Animals. Not a drop of water 

 can be left stagnant for even an hour without becoming at 

 once densely peopled with crowds of animals, which are 

 so very minute that but very few of them can be seen by 

 the naked eye ; in fact, it is scarcely likely that you would 

 believe all that I could tell you about them, unless you were 

 to use a microscope, so as to examine them for yourself. 

 These minute creatures are called Infusoria or Animalcules. 

 Their bodies are various in form, and are very numerous. 

 Most of them move freely through the water by means of 

 their cilia ; some, however, become fixed, and then the 

 cilia, by their motion, produce a current, which brings 

 particles of food to the mouth ; for I must point out to 

 you that the infusoria possess mouths, for this fact will 

 distinguish them from others which I shall speak of 

 presently. One of these animals, called the Vorticella, 

 is attached to duckweed, or the stalks of other vegetable 

 structures in ponds and pools, by a long hair-like stalk, 

 which it can extend or contract. Another, called the 

 Stentor, is in shape like a 

 trumpet, and is fixed by its 

 narrow end, whilst its wide 

 mouth is surrounded by cilia. 

 Fig. 1 10 shows a Flask Ani- 

 malcula (Enchelys), from 

 which you will see its modes of 

 feeding. The minute particles 

 having been drawn into the 

 mouth, are gradually swallowed, 

 and each fresh morsel pushes 

 the former one farther down. As many of these particles are 

 seen at once through the transparent substance of whicn 

 they are composed, the animals were at one time called 



