INFUSORIA. 



707 



which constitute a higher branch, but microscopic and universal, and include 



those called Flagellate, Ciliate, and Tentaculate. The first have whip-like 



cilia, or feelers, or filaments, which are ever in motion to cause a movement 



of the water and carry food to the animal. You will find plenty of infusoria 



in any stagnant water, and when placed under the microscope a mouth may 



be perceived, but no stomach, nor any apparent receptacle for food, which 



appears to enter at once into the body substance. The other kinds 



capture their food by seizure by the 



tentacles, or by agitating the cilia, 



like the flagellata, and thus whipping 



the nourishment towards the mouth, 



as children will draw in a toy boat 



to land by agitating the water in the 



given direction. These cilia, or hairs, 



serve for organs of locomotion as well 



as of capture. These creatures are 



called Infusoria, because they exist 



in vegetable "infusions " exposed to 



the atmosphere. 



Decaying vegetable or animal 

 substances, such as the leaves of 

 trees, grass, a piece of flesh, etc., 

 affused with water and exposed to 

 air and warmth, will speedily, upon 

 microscopic examination, be found 

 peopled with numbers of most active 

 minute creatures of the most varied 

 forms. These animalcules are found 

 also in the stagnant pools around 

 our cities, in the waters of rivers, 

 harbours, and lakes, and even in the 

 ocean. 



In' reference to the origin of 

 these animalcules, the view was long 

 entertained that they were generated 

 spontaneously, that the decaying 

 vegetable and animal substances were 

 decomposed and resolved into these simple beings. More accurate experi- 

 ments have shown, however, that the infusoria are produced from ova, or 

 germs, which are probably carried about in the.dried-up state, in the form of 

 minute particles of dust,* ready to develop themselves in any spot which 

 may afford them the requisite moisture and nutriment. In this respect they 



*That the presence of millions of such ova in the air should not be detected, will appear 

 very natural indeed, if we reflect that the animalcules are only T ^ 7 to ^V? part of a line in 

 diameter, and that the ova are a thousand times smaller. 



Fig. 830. Structure of polypidoms. 



