25 



of siinliglit, Tlie establlshinent of an aquariiiiii therefore 

 demands, as one of the conditions of success, an abundance 

 of light, the same conditions, in fact, necessary to life in 

 the pond. The closer we apj^roach this ideal, the greater 

 the success will be. 



The establishment of a marine aquarium at AVashington 

 by the United States Fish Commission has furnislied the 

 means of making many interesting observations, and has 

 I)ractically demonstrated that it is i^ossible to maintain 

 marine aquaria away from the sea without very great diffi- 

 culty and without greater mortality, probably, than is usual 

 where the water may be pumped directly from the sea. 

 The chief difficulties are in the transportation of fishes 

 from the sea without injury, some of them being of veiy 

 delicate nature. This is more easily accomplished at a 

 time when the temperature is moderate, being neither at 

 one extreme nor the other. The control of temperature in 

 the aquarium, owing to our extremes of heat and cold, is 

 a matter of some difficulty, but must be overcome as an 

 element of success. The more nearly we can approach an 

 equalization of temperature, the more satisfactory will be 

 the results, no doubt. 



The Washington Marine Aquarium is built in a green- 

 housedike annex to the central station of the United States 

 Hsli Commission. This style of structure affords the 

 necessary light. Twenty-four aquaria, of from sixty to 

 seventy hve-gallons capacity each, are arranged to form a 

 gallery in a cavern or grotto built in imitation of rock, 

 which is lighted wholly by the daylight passing through 

 the water from above; 6,<»ti() gallons of water are used. 

 This is pumped fi-om a brick reservoir outside to a tank at 

 an elevation of about forty feet, from which it descends 

 under the resulting pressure — about twenty pounds — into 

 the aquaria through very small glass nozzles, thus effect- 

 ing a most efficient aeration. The materials of construction 

 of aquaria, reservoir tanks, circulatory apparatus, etc. — 



