BRANCH PROTOZOA: THE ONE-CELLED ANIMALS 79 



cilia. Many of the familiar Protozoa of the fresh-water 

 ponds always have two whiplash-like flagella projecting 

 from one end of the body. By means of the lashing of 

 these flagella in the water the tiny creature swims about. 

 Others have many hundreds of fine short cilia scattered, 

 sometimes in regular rows, over the body-surface. The 

 Protozoan swims by the vibration of these cilia in the 

 water. 



There is no stagnant pool, no water standing exposed 

 in watering-trough or bar- 

 rel which does not contain 

 thousands of individuals of 

 the one-celled animals. 

 And in any such stagnant 

 water there may always be 

 found several or many dif- 

 ferent kinds or species. A 

 drop of this water examined 

 with the compound micro- 

 . scope will prove to be a 

 tiny world (all an ocean) 

 with most of its animals and 

 plants one-celled in struc- 

 ture. A few many-celled 

 animals will be found in it 

 preying on the one-celled 

 ones. There are sudden 

 and violent deaths here, and 

 births (by fission of the 

 parent) and active locomo- 

 tion and food-getting and 

 growth and all of the busi- 

 nesses and functions of life 

 which we are accustomed 

 world of larger animals. 



which has the nucleus in the shai 

 of a string or chain of bead- 



FIG. 10. Stcntor sp. ; a protozoan 

 which may be fixed, like Vortifellu, 

 or free-swimming, at will, and 



hape 

 -like 



bodies. The figure shows a single 

 individual as it appeared when fixed, 

 with elongate, stalked bodv, and as 

 it appeared when swimming about, 

 with contracted body. (From life.) 



to see in the more familiar 



