408 Mr, Warington, on the Aquarium, [March 27, 



confined to shallow waters, so that a selection of the inhabitants 

 must be made. 



Heat. — The proper control of this agent is also most material 

 to the well-being of these tanks, for experience has proved that an 

 increase or diminution of temperature beyond certain limits acts 

 most fatally on many of the creatures usually kept. These limits 

 appear to be from 45^ to 75° Fahrenheit. The mean temperature 

 of the ocean is estimated to be about 56° ; and this does not vary 

 more than 12° throughout the varying seasons of the year, showing 

 the extreme limits to be from 44° to 68°. Great care should there- 

 fore be taken to afford as much protection as possible, by the 

 arrangement of the rockwork, bpth from the sun's rays by day, and 

 the effects of radiation at night, as from the small volume of water 

 contained in the aquarium these effects are rapidly produced. 



Food. — As many persons, to whom those interested in these 

 matters have naturally looked for instruction, have decried the idea 

 of feeding, it will be necessary to offer a few remarks on that point. 

 How creatures, so voracious as most of the denizens of the water 

 are, both fresh and marine, are to thrive without food, is a question 

 it would be difficult to solve ; common sense would say they must 

 gradually decrease in size, and ultimately die from starvation. 

 The food employed should be in accordance with the habits of the 

 iish, &c. For the vegetable and mud feeders, vermicelli, crushed 

 small, with now and then a little animal food, as worms, small 

 shreds of meat, rasped boiled liver, and the like. For the marine 

 creatures, raw meat dried in the sun and moistened when used, 

 answers very well. Oyster, mussel, cockle, raw fish, shrimps, and 

 the like matters may be employed ; these should be cut or pulled into 

 very small pieces, and never more given than they can at once 

 appropriate ; and if rejected by one it should be transferred to 

 another, or removed from the tank. In the case of actinia, they 

 require, from their fixed position, that the food should be guided to 

 their tentacles ; and if the animal food, of whatever kind, is soaked 

 in a little water, and the water thus impregnated with animal fluids 

 be dropped in moderate quantity into the tank it will afford food for 

 the small entomostracha and smaller creatures with which the water 

 abounds, and which constitute the food for many of them. 



A few observations were also made on the construction of a 

 microscope for the purpose of employment in connection with the 

 aquarium, and the method in which such- an instrument could be 

 used. 



[R. W.] 



