228 



EECEEATIVB SCIENCE. 



debri3 tlirougla her laboratory, and the very 

 Bonrce of life for which they pined and 

 perished — oxygen — is poured in in large 

 measure, and the corruption is quickly 

 changed to sweetness. Of the once sportive 

 fishes some portions have become air, other 

 portions have become water, but the chief of 

 their bulk lives already in the vegetation 

 which hides their grave, and the moving 

 throng with which that vegetation is peopled. 

 God's purpose in the working of the laws in 

 obedience to which these changes have taken 

 place, is manifestly to keep ever true that 

 balance of life and death of which He holds 

 the beam in His own hands. 



But my aquarium which has not thus 

 been interfered with, presents already a simi- 

 lar scene of life and bustle. When first sup- 

 plied, the milky -looking water was abundantly 

 full of gaseous matters, and every part of the 

 rough rockwork was, for a time, studded 

 with silvery globules. The fishes consumed 

 all that in the process of breathing. As the 

 water passed through their gills the oxygen 

 was absorbed ; that oxygen, by a process of re- 

 fined chemistry, and perhaps by the help of 

 iron also, gave their gills a bright red colour, 

 gave their blood its red colour too, and by 

 other processes not less refined, sustained the 

 "balance of life's functions within them, for 

 without it they must perish. We believe 

 that not the airiest particle of earth, atmos- 

 phere, or water, nor the most minute globule 

 of condensed moisture, or the most infinite- 

 simal point of meteoric dust, can ever be lost, 

 at least during Time, from the fabric of the 

 universe. My fishes tell me that the oxygen 

 they absorb from the water, they again return 

 to it, but in another form. They inspire 

 oxygen and ex'pire carbonic acid, just as a 

 man does, and every other living creature 

 that moveth upon the face of all the earth. 

 Is it within the reach of human power, even 

 when reason, imagination, and fancy combine 

 together as a bold triad to look direct upon 

 a fact, to appreciate that principle of terres- 



trial life by which animal and vegetable or* 

 ganisms reciprocally labour to maintain the 

 balance of atmospheric purity ? The carbonic 

 acid given ofi" by the animal is poison to it, 

 if it accumulate while the supply of oxygen 

 is cut short. It was carbonic acid as much 

 as absefice of oxygen that killed our fishes 

 just now, for though inhabitants of water 

 they were not the less suffocated. Therefore 

 I see will/, in the tank that has been left alone, 

 plants have cast anchor on the glass walls, 

 the brown pebbles, and the gray blocks of 

 sandstone rock. My fishes breathe and 

 breathe. If their numbers are properly pro- 

 portioned to the area tliey occupy, they will 

 never exhaust the water of oxygen, never 

 render it foetid with carbonic acid, so long 

 as one necessity of vegetable life — light — is 

 allowed to use its active influence to paint 

 the plants green, even as oxygen gives a san- 

 guine hue to the gills or lungs of the fishes. 

 To those plants the carbonic acid which the 

 fishes expire day and night, is as essential as 

 oxygen is to the animal economy, and thus, 

 without introducing a single scrap of any 

 living plant, the balance is sustained, and 

 death seems to be kept at a distance. If at 

 first I threw in a tuft of callitriche or anacha- 

 ris, or any other true aquatic vegetable, oxy- 

 gen would be supplied abundantly ; and in 

 practice it might be well to begin so, because 

 some little time elapses ere the seeds of the 

 microscopic forest, the tops of whose trees pre- 

 sent to the eye but a felt-like coating of super- 

 ficial greenness, are developed into true plants; 

 though with a fair amount of indirect day- 

 light, and at certain seasons of the year, a few 

 hours suffice to set the vegetative process, 

 with all its proper consequences, in full ac- 

 tion. Many of the readers of this paper wiU 

 call to mind the aquarium that stands in my 

 entrance hall. It contains twenty fishes, 

 large and small, and not a single scrap of 

 vegetation except what has been developed 

 in siitt by spontaneous generation. It is 

 three years since that was fitted and stocked, 



