4: POPULAR HISTORY OF THE AQUARIUM. 



aerated, a fresh supply of the vital element may thus be 

 mtroduced and its power of sustaining animal existence 

 proportionally prolonged. 



But it is now found that water-plants, properly acted 

 upon by the light and under other suitable conditions, will, 

 instead of taking from, add to, the proportion of oxygen 

 present, and will thus restore the balance, without mecha- 

 nical aeration. Thus, tanks of water with plants and 

 animals, as collected by the first experimenters years ago, 

 still exist with their tenants, living and breeding healthily ; 

 and although the water has never been changed, it is as 

 clear as when first put in, and as capable of sustaining life. 



Experiments and Adoption of Plan. 



Although many partial experiments may have been made 

 with a view to keeping animals in water for the purposes 

 of observation, and many interesting details in marine and 

 fresh-water zoology have resulted, we may consider that 

 the first serious and systematic attempt to keep a Water 

 Vivarium, in its true sense, was made by Mr. Eobert War- 

 rington, of Apothecaries' Hall. That gentleman's early 

 experiments were communicated to the Chemical Society 

 in 1850, in a paper " On the Adjustments of the Relations 



