12 



INTRODUCTION TO ZOOLOGY 



Unicdluhir Furms ultkh possess Cilia. 



Other relntions of the A7iioeb;i have adopted a more active 

 means of jn'oteetiiig themselves from dangei-, 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" {dliurii, an eye- 

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

 and l)y their rapid vibration propel the whole body forward 

 in the water. 



Fig. 3.— J, BoiJo stiltons ; B, I'l'miifOivlain. 

 , Nucl-^u.s ; y"/", laicro-niK-leus ; '■>ji>. vai:\ contractile \acuole i'ormiii;,^ 

 CO;/. (■",(■", contractile \'acuole discriaii^in;^^ 



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

 i ff Monad cilia, as in the Springing Monad Bodo saltans (or 

 Heteromila 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 continriou.s coat of cilia, 

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

 genus is also more highly organised than Amoeba 

 Anhnalcule^ in having 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. Punwwecium 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 



