CONDITIONS OF LIGHT, ETC. 



ROCKWORK FOR THE AQUARIUM 



Picturesque effects in the aquarium may be produced by the introduc- 

 tion of rockwork and other natural objects. Pomice adapts itself well for 

 this purpose and is easily worked. Odd pieces fastened together to form 

 a grotto or rockery may have the surfaces hollowed out to contain soil 

 and sand in which plants may be grown, or form a screen behind which 

 brackets for small flower pots may be constructed. Tuftstone is also to 

 be recommended, as very handsome odd pieces may be obtained and nat- 

 ural effects produced by their tasteful arrangement. Selinite or gypsum 

 may be introduced, as it is not only handsome in appearance but dissolv- 

 ing slowly in the water, it furnishes lime, necessary to the molluscs and 

 other animal life. Small pieces of plaster of paris will also serve for this 

 purpose. Mica schist, quartz, feldspar, agate, rock crystals and other 

 minerals are effective, or water-worn stones to which aquatic plants are 

 attached may be introduced, but all other objects not natural to a water 

 garden are in questionable taste. All objects should be clean, and soaked 

 for some time in water before they are put into the aquarium. 



