EECEEATIVE SCIENCE. 



229^ 



and committed to tlie management of Nature, 

 witli the sole exception of the external aid 

 afforded by regular supplies of food for its 

 inmates, which need not be taken account of, 

 now that we are considering it as a world in 

 which the balance of life and death is sus- 

 tained by the operation of principles ordained 

 by the Creator. 



It is when we leave the principles and 

 attempt to classify the details of the scheme 

 that we become bewildered. The smooth 

 revolution of the flywheel and the noiseless 

 oscillation of the piston, convince the impro- 

 fessional observer of a great engine, that 

 mechanical motions are possessed of poetry ; 

 but if he would analyze the relations of the 

 cog-wheels, the indications of the " gover- 

 nor," the "guage,"and the pressure-valve, 

 he must descend to hard facts, and forget for 

 a while the sublime suggestions of a system of 

 mechanism that throbs like a living creature. 

 Admit a full glare of summer sun to the 

 aquarium, and forthwith the water loses its 

 pellucid fluidity, and becomes deeply tinged 

 throughout of a dull green, as if some pig- 

 ment had been dissolved in it. Instead of 

 plants attached to stones and glass only, and 

 animals that float unseen, the whole of the 

 water is occupied by visible masses of animal 

 and vegetable life ; and if the fishes suffer it 

 will be from undue heat, not from the 

 addition to the element in which they live of 

 this new mass of being. Shut out the sun- 

 shine, let the fresh air play over the surface 

 of the water, let moderate daylight stream 

 through it as before, and speedily the green 

 fog clears away, the water again becomes 

 transparent, and the balance is restored. 

 Monas, euglena, uvella, cryptomonas, 

 goniura, and other wondrous infusoria, may 

 be detected as constituents of the cloudy 

 mass -v^'hile it lasts, called into being be- 

 cause the conditions of the tank were such 

 as they required, as if life in embryo ■yvas 

 everywhere locked up until the moment 

 came for its liberation, and some particular 



circumstance was the talisman to set it free ; 

 or if we consider created forms to be mar- 

 shalled in grand procession, may we not ex- 

 pect that every tribe will hurry to its 

 appointed place the instant that a door is 

 opened ? 



Microscopists have long been at war, but 

 without bloodshed, as to the place to be 

 assigned to certain organic forms which are 

 hidden from our common eyesight. While 

 the war goes on as to whether desmidiacse 

 and diatomacese be animal or vegetable, or 

 both, let facts suffice us here in the study of 

 the aquarium. Does an animal exhale car- 

 bonic acid ? Yes. Well, here are plants or 

 animals, concerned in keeping up the balance, 

 which exhale oxygen, and their name is 

 legion. Volvox globator and the bacillarife 

 labour as hard to supply the fishes with the 

 life-sustaining gas as do the silken threads 

 of verdure that line the glass like a carpet. 

 Is the possession of starch a distinctive 

 feature of the vegetable ? Perhaps so. 

 Truly here are desmidiacaj that contain 

 starch, and if I make the possession of cilia 

 the test for assigning certain forms to the 

 animal kingdom, I find in the aquarium 

 spores of algae furnished with them. Motion 

 I know to be no test, because alga; spores 

 dance through the water gaily till they find 

 a resting-place, and when the aquarium was 

 first filled, it was by dancing they at last 

 found where to pitch their tents, and cease 

 their nomad wanderings. But they all work 

 together to sustain the balance, and the law 

 of "give and take" prevails amongst them — 

 the stentor devoiu-s the oscillatoria;, rotatoria, 

 and monads, and the hydras swallow all ; 

 every darting speck is a tomb wherein some 

 smaller speck of life is to be buried, and life 

 thus prospers on the decay it is itself under- 

 going. 



But all this whUe a fine deposit slowly 

 settles among the pebbles, which form the 

 lower stratum of this watery world. Be- 

 tween the stones a fine alluvial silt coUects 



