FIELD BOOK OF PONDS AND STREAMS 



the insects or in water which has been brought in from ponds. 

 They are selected because either singly or in clusters they are 

 large enough to be seen through a hand-lens, sometimes even 

 with the naked eye. 



Fig. 48. — Stentor. 



Stentor. — These are trumpet-shaped animals which are 

 transparent blue-green or whitish (Fig. 48). Against a white 

 background the blue-green ones can be seen with the naked 

 eye. They are often very abundant in the water about sphag- 

 num moss. 



MinMiiiniluill!'Wirt'[Hirilr,M_rr.;.,,,.yii.i,,,,,;)|j,^^ 



Fig. 49. — Spirostomum. 



Spirostomum. — Spirostomum (Fig. 49) occurs in shaded, 

 dark-bottomed pools, each animal appearing like a white line 

 about the length of a dash. Large numbers of them some- 

 times whiten the surface of the water. 



Paramoecium. — Paramoecia (Fig. 50) show only as white, 

 rapidly-moving particles in dishes of pond water , or as a 

 white edge on the water line when they are crowded together 

 on the surface of dishes of pond trash which have been left 

 standing. 



Bell-animals, Vorticella, Epistylis, Carchesium. — Colonies of 



56 



