302 



CIVIC BIOLOGY 



and danger of a stoppage of escape jDipe, and consequent flooding of 

 building, is too great a risk. The absolute rule should be that one j^erson 

 shall take the sole responsibility for an aquarium, and no one else be per- 

 mitted to put anything in or take anything out of it. As long as the aqua- 

 rium is properly balanced and managed, the water need never be changed. 

 Water is always water, and as it evaporates, clean pond or brook water 



Fig. 141. Biological Laboratory, Cleveland Normal Training School 



A^'iew of the. west end, showing three of the four large aquaria built into the wall 

 under the windows, and a small greenhouse opening out of the laboratory i 



must be added to keep the level about constant. If adding any consider- 

 able quantity, allow the water to stand in the room a day, or until it is 

 of the same temperature as that in the aquarium; for even small 

 changes of temperature, if sudden, may be injurious, or even fatal, to 

 some fishes. The hand should never be put into the aquarium ; it carries 

 too many troublesome bacteria. Use the proper tools — dipping-tubes and 

 siphons, dijvnets and scrapers. A spirit of good-natured rivalry should be 



1 The architect overruled the location of these aquaria in the north wall 

 and changed their specifications. They should be two feet, instead of about 

 one foot, deep, bringing the bottom two feet from the floor and giving 

 double the depth of water. The glass roof, if present at all, should be raised 

 to the middle bar of the window, and the flap, which can be lowered to 

 shut the space above the aquaria from the room, should be two feet wide. 



