AQUABIUJC. 



year (1849), and chose for my first experiment two small 

 gold fish. These I placed in a glass vessel, with some mould, 

 stones, &c., and in it I planted a small root of vaUisneria. 



" All appeared to go on well for a time, nntil a portion of 

 the plant, decaying, rendered the water turbid, and caused a 

 growth of mucus, which adhered to the side of the glass, 

 impeding the entrance of light into the interior, and with 

 this stopped the supply of oxygen from the plants. I had 

 therefore recourse to the useful services of the Water Snail ; 

 two or three of which T introduced into the vessel. These 

 scavengers soon cleared away the decomposed matter; and 

 from that time all went on well." 



The facts are simply these. Vegetable life can only be sustained 

 where carbon is present. This is derived from the oarbonic- 

 a^id gas thrown off by all animals in the process of breathing, 

 as well as by the decomposition of animal and vegetable re- 

 mains. Nitrogen also enters into the structure of most plants, 

 being found in that portion called gluten. Carbon, however, is 

 the principal element of the vegetable world, and enters into 

 and forms the more solid parts of the structure of plants ; but. 

 essential as it is to vegetable Ufe, it would soon poison the 

 water of an aquarium were it not absorbed by the plants con- 

 tained therein. Plants, on the contrary, when acted upon by 

 the direct rays of light, generate and throw off oxygen, which 

 is as essential to animal life as carbon is to vegetable life, the 

 blood of animals requiring to be perpetually purified by the 

 continual addition to it of this elementary principle; and 

 when this cannot be obtained, or is not present in sufficient 

 quantity, the blood of the animal becomes impure, and life 

 consequently languishes, or altogether fails; upon the same prin- 

 ciple that a lighted candle expires in an unventilated well or pit. 

 By bearing in mind and adopting the principle of natural che- 

 mistry, that the element oxygen which the plants refuse to absorb 

 is the first necessary of life to the fishes, while the carbon thrown 

 off by the fishes forms the sole food of the plants, you furnish 

 both your animals and vegetables with the indispensable re- 

 quirements by which breath is preserved and life maintained. 



You may either purchase your water-plants of a dealer in 

 aquaria, or you may save your money and enjoy a pleasant 

 country excursion, by a personal study of pond botany. On 

 account of its long and bright-green leaves, the VaEisneria is 

 well suited as a plant for the aquaria. It has perennial roots.j 

 and requires but slight" depth of soU. The economy of this 



