The Aquarium 23 



fore harmless. If, however, it should be 

 considerably colder or warmer, the plants 

 should be kept for a few hours in the same 

 room and temperature with the aquarium 

 and then planted. In grouping aquatics 

 care should be taken that they have ample 

 room for development, and that they are so 

 arranged as to form the pleasing picture of 

 a little submerged garden. They should be 

 placed at least two inches away from the 

 glass, so that the latter can be cleaned with- 

 out damage to the plants. Now also is the 

 time to place such plants as will grow near, 

 and above the surface of the water, in suit- 

 able positions upon the rock. A few of the 

 best varieties for this purpose will be de- 

 scribed in another part of the book. 



As mentioned before, plants perform cer- 

 tain functions of the greatest importance in 

 the aquarium. They have to furnish the 

 oxygen without which animal life cannot 

 exist. Fishes, as well as amphibians, and 

 even insects, have respiratory organs with 



