MICROSCOPE IN AQUARIUM WORK 



237 



these organisms and thus be apt to deceive the observer as to the 

 actual food value contained in the water. Also with high magnifica- 

 tion the field of vision and the area of sharp focus are smaller, while 

 movements are apparently much more rapid, making observation 

 difficult. 



The majority of the valuable organisms are rotifers. These move 

 in a steady, revolving or rotating manner. On page 51 will be 

 found instructions for propagating these organisms for purposes of 

 feeding young fish. Most rotifers can be readily identified as such 

 because they swim through the water by means of circlets of hairs 



Fig. 223. Commox Forms of Microscopic Animal Life in Fresh Water 



(Greatly magnified) 



1. Lo.xoDES, a very common form. 



2. Ceratium, a very common form, especially in ponds and lakes. 



3. Paramaecium, a very common form, the slipper animalcule. 



4. Bursaria, a very common form, one of the largest. 



5. .Stylonycha, a very common form, found everywhere. 



6. Phacus, not so common as the above numbers. 



7. Spirostomum, common everywhere. 



8. EuGLENA, common everywhere. 



9. Chilodon, common everywhere. 



10. Trachelocerca, common everywhere, the swan animalcule. 



11. EupoLOTES, not an aquarium in America without examples. 

 12. DiDiNiuM, predaceous, feeds on paramaecium and others. 



13. Trachelocerca, small but plentiful. 

 14. CoLEPS, the barrel animalcule, common. 



