THE FISH.
It was inevitable that the free element, the Sea, should, sooner or later, produce a creature like unto herself, eminently free, undulating and fluid, gliding like the wave, but with a marvellous mobility founded on an interior miracle greater still, on an internal organization at once delicate and strong, and very elastic, such as no creature had previously ever approached to.
The Mollusc, crawling on its belly, was the poor serf of the glebe, and the Poulpe, with all his swelling and threatening pride, swimming badly and unable to walk or crawl at all, was still more completely the serf of chance. The warlike crustaceæ, by turns so high and so low, alternately the terror and derision of all, were at times the slave, the prey of even the weakest creatures.
Great and terrible servitudes those; how were they to be remedied?
Strength is the very soul of liberty. From the very beginning, Life seems gradually but confusedly to have sought the creation of a central axis which should give the creature unity, and enormously increase its strength of motion. The rayed family and the molluscs exhibit a presentiment, a partial sketch of it, but they were too much led away by the insoluble problem of the exterior defence. The covering, always the covering, was that which constantly occupied the attention of these poor beings. As to that one point, they produced masterpieces; the thorny ball of the Oursin, the shell at once open and closed of the Haliotide, and, finally, the armors of jointed pieces of the Crustaceæ, are the very perfection of armor at once defensive and terribly offensive. What more could be required? It would seem, nothing.
Nothing? Say, rather, everything. Let us have a creature who shall trust entirely to motion, a creature of freedom and audacity, that shall look down upon all these creatures as infirm, or miserably slow; a creature that shall consider the envelope as a merely secondary matter, and concentrate his whole strength within himself.
The crustaceæ shroud themselves, as it were, in an exterior skeleton. The fish has his skeleton within, to which nerves, muscles, and all organs are attached.
This seems a fanciful invention, and one quite contrary to good sense; to place the hard and the solid beneath the thick covering of the soft! To place the bone, so useful without, precisely where it seems it must be so useless! The crustaceæ must needs have laughed in derision when they first saw the short, thick, soft fish of the Indian Ocean, for instance, without defensive armor, having no strength save inwardly, protected only by its oily fluidity, by the exuberant mucus that surrounds it, and which by degrees consolidates into elastic scales, a slight cuirass, which ever yielding, never yields entirely.
It was a revolution comparable to that of Gustavus Adolphus, when he relieved his soldiery of their heavy iron armor, and covered their breasts only with the at once stout and yielding buff leather. A late revolution, but a wise one.
Our fish, being no longer confined like the crab or lobster, imprisoned in armor, is at the same time relieved from the cruel condition inseparable from that armor, the moulting, with its attendant danger, weakness, struggle, and enormously wasteful expenditure of strength. Like the superior animals and man, he moults slowly. He economises and hoards up strength, and creates for himself the treasure of a powerful nervous system, with numerous telegraphic threads that connect spine and brain. Even when the bone is soft or absent, and the fish preserves its embryonic appearance, he has nevertheless his great harmony in that abundant provision of nervous threads.