i66 NATURE-STUDY 



Take the pupils out to the pond, brook, lake, or river, and 

 collect the things to be put into the aquaria. This should 

 be more than a mere collecting trip. Have the children note 

 as far as possible the conditions under which the creatures 

 live, perhaps the food needed, the depth of the water in 

 which they live, etc. This will teach them something of the 

 habits of the creatures, which should be utilized in fitting up 

 the aquarium. Gather some of the plants among which the 

 animals live, perhaps some of the dead leaves and twigs at 



FIG. 35. Aquaria. 



the bottom of the water, as these will furnish food or natural 

 shelter for the animals. 



In case of most aquatic insects a mud or ooze bottom seems 

 best for their aquarium. The water from the pond whence 

 they came also is often better than well or city water. For 

 fishes and clams the bottom may be of clean sand. Pretty 

 stones and pieces of coral and seashells placed in the aqua- 

 rium will make it more attractive. 



The best way to keep the water fresh and supplied with 

 oxygen is to place in it green aquatic plants. These give off 

 oxygen in the sunlight. This is often seen in a jar with a 

 mass of green algae in the water when- the sun is shining on 

 it. There are small bubbles of oxygen upon the mass. Small 

 aquaria, with not too many animals, may be kept for months 



