22 INTRODUCTION TO ZOOLOGY chap, i 



a piece of chalk rock and examine the broken fragments of shells 

 in it. Sketch from the prepared slide a few typical shells, naming 

 them, if possible, by reference to the article " Protozoa " in the 

 Encyclopmdia Britannica, or some other book, such as The Fora- 

 minifera, by F. Chapman. 



3. Mount a drop of water in which a few decaying flower-stems 

 have been left for a week, search for the rapidly moving Para- 

 moecium. If these organisms are present, put a few shreds of 

 cotton-wool across the water to check their movements, cover with 

 a cover-slip and examine carefully, identifying the structures shown 

 in Fig. 3, B. 



4. Examine water-weeds from a pond ; some may seem to have 

 a delicate white fur on stem or leaf; this very probably may be 

 due to the presence of many Vorticellae,^ or other allied organisms. 

 Study all you can find, making sketches and notes. Identify 

 where you can by the aid of the article " Protozoa " referred to above. 



^ Supplied by T. Bolton. 



