PRESERVING WATER ANIMALS 



Water plants should be set in this, good ones for the aquarium 

 being Elodea, AlynopJiyllum, and wild celery or Vallisfieria 

 (^ig- 35) • The water should be added gently and then 



Fig. 35. — A balanced aquarium showing: i, Elodea; 

 2, Myriophyllum; 3, Vallisneria; 4, mayfly nymph; 5, 

 adult mayfly; 5a, cast nymphal skin of mayfly; 6, tad- 

 pole; 7, snail; 8, snail's eggs seen through reading 

 glass. 



left to settle for a couple of days. Many things will live well 

 in such an aquarium if they have plenty "of oxygen and a 

 little food. Snails will lay their eggs on the sides of the jar; 

 such pond mayflies as CallihcBtis and Blasturus, and dragon- 

 flies and tadpoles will thrive here. Do not crowd the ani- 

 mals and do not mix the vegetarians and the carnivores; 

 after such a mixture there will be only one kind left. 



It is better to have several small aquaria (e.g., 6x3x5 



inches) than one large one. 

 If aquaria are made of plate glass, things can be photo- 



39 



