142 NATURE-STUDY REVIEW 



The same procedure will be followed in regard to choice of ani T 

 mals for the aquariums. There will be the desire to put in every 

 kind of thing that "wiggles" and every individual of each kind 

 that can be caught, which will have dire results if the work is 

 unrestrained. Sometimes it is a question how much restraint 

 should be used, as many things are learned by failure, if the failure 

 is rightly interpreted. 



If the big sunfish, "or punkin-seed," so beautiful in coloi, 

 "gobbles up" all other animals possible, and rushes around so vig- 

 orously as to uproot most of the plants, he will soon prove himself 

 an undesirable occupant, and some other fish, smaller or less 

 aggressive, be substituted, while he goes back to his native pond. 



Or if the big dragonfly nymph devours all smaller insects that 

 cannot evade it, or chews off the polywog's or fish's tail and even 

 fastens upon the body of a snail before it can shrink back into its 

 shell, it, too, will be removed to safer quarters and fed upon less 

 valuable food. But it will be sufficient reward for all work if some 

 day he is watched as he crawls up on a stem above water, and, 

 hanging there, splits his hard skin down the back and with distinct 

 effort pulls himself out. Then what a delight to watch him., 

 after a brief rest from the struggle, transform the four limp lumps 

 on his back into gauzy, veined wings that when dry glisten and 

 glow in the sunlight like dewdrops or diamonds! 



When he is thoroughly dry he flies off darting so quickly that the 

 eye can hardly follow him, but, if one knows what to look for, 

 it may be possible to see that some mosquitoes and gnats have 

 disappeared along his route, and one realizes that the big appetite 

 that made him a scourge in the aquarium is a blessing when it 

 causes the removal of so many of the pests that have made careful 

 study of ponds and marshes a trial of one's patience. 



Gradually much is learned of the proper association of different 

 forms of animal life, and several jars may be stocked to represent 

 groups as they are observed in field trips. 



The proper kinds and amount of food are learned by experience; 

 overfeeding with a consequent fouling of the water by decay of the 

 surplus is one of the first mistakes. 



The proper lighting of the aquarium must be studied ; too little 

 light resulting in starving the green plants, with consequent suffer- 

 ing or death of animals that live entirely within the water, from 



