OCEAN GARDENS; 



people of cold northern countries; and much more 

 so than the recent introduction of the giraffe or 

 hippopotamus, although they have never been seen 

 in Europe since the days of the E^omans. 



Those principles, the knowledge of which was 

 requisite to enable us thus to view the wonders of 

 the ocean in their living state in an Aquarium, were 

 not mastered at once, or by one man, or in one 

 generation. The nature of certain relations between 

 animal and vegetable life, upon which they are 

 founded, was first advanced by Priestley, towards 

 the close of the last century, who proved that plants 

 give forth the oxygen necessary to animal life. The 

 learned Ingenhauss, a native of Breda, but who 

 principally resided in England, defined this princi- 

 ple still more clearly, in a work the title of which 

 pretty fully explains the entire nature of hisT dis- 

 covery. It was published in Erench, at Leyden, in 

 1778, and in London, in English, in 1779. The 

 Erench edition is before me, the title of which I 

 translate, " Experiments upon Plants, which prove 

 their important influence in the purification of the 

 atmospheric air when they are exposed to the rays 

 of the sun, and the contrary results which ensue 

 when they are placed in the shade, or during the 

 night." The action of the sun's rays in disengaging 



20 



