146 THE SEA-SIDE AND AQUARIUM. 



more especially such, as it is necessary to introduce 

 into a good Aquarium. The Algas not only add to 

 its picturesqueness and beauty, but their presence 

 is absolutely essential for the existence and health 

 of its occupants. 



This combination which we urge, of sea-weed and 

 sea animals in the Aquarium, is just following out 

 the laws of Nature, as apparent to all who will watch 

 an ocean in miniature at the sea-side. There the 

 most inattentive observer cannot fail to perceive that 

 wherever living creatures are found, there are also 

 plants and sea- weeds of various kinds growing in 

 luxurious profusion, " the one being essential to the 

 other in supporting the life of both." 



" The animal and vegetable respirations counter- 

 balance each other, the animal's blood being purified 

 by the oxygen given off by the plants the plants 

 fed by the carbonic acid breathed by the. animals." 

 When your Aquarium has been established a short 

 time, if all goes well, you will perceive " thousands 

 of tiny globules (like quicksilver balls of various sizes) 

 forming on every plant, and over all the stones where 

 the infant vegetation is beginning to grow, and these 

 globules presently rise in rapid succession to the surface 

 all over the vessel. This process goes on, without in- 

 termission, so long as the rays of the sun are uninter- 

 rupted. These bubbles consist of pure oxygen given 

 out by the plants, under the influence of light, and 

 to this oxygen the animals in the tank owe their life." * 

 * Vide Grosse's "Aquarium." 



