12 



INTRODUCTION TO ZOOLOGY 

 Unicellular Forms which possess Cilia. 



CHAP. 



Other relations of the Amoeba have adopted a more active 

 means of protecting themselves from danger, for instead of, 

 or as well as a protective coat, they have developed certain 

 very simple organs of locomotion, consisting of delicate 

 threads of protoplasm, known as "cilia" (cUiwm, an eye- 

 lash), which project from the general surface of the body, 

 and by their rapid vibration propel the whole body forward 

 in the water. 



f\. 



FIG. 3. A, Bodo salterns; B, 

 nu', Nucleus ; nu", micro-nucleus ; con. vac', contractile vacuole forming ; 

 con. vac", contractile vacuole discharging. 



Some forms have only one, or a pair, of such 

 Tng Monad c ^ a> as * n tne Springing Monad Bodo saltans (or 

 Heteromita rostrata) (Fig. 3, A\ a very minute form, 

 found in water in which organic matter has been allowed to 

 decay. Others are covered by a continuous coat of cilia, 

 as in the Slipper Animalcule Pammoecium (Fig. 3, B). This 

 genus is also more highly organised than Amoeba 

 Animalcule* * n nav i n a more definite form, and a special funnel- 

 like depression at one point of the body, through 

 which alone food is absorbed, and which functions, therefore, 

 as a mouth. Paramoecium is an interesting organism to study. 

 It is larger than most unicellular organisms, being just 

 visible as a speck to the naked eye ; a full account of it is 



