On that leg grows, amid another copse of the grey polypes, a delicate straw-coloured Sertularia, branch on branch of tiny double combs, each tooth of the comb being a tube containing a living flower; on another leg another Sertularia, coarser, but still beautiful; and round it again has trained itself, parasitic on the parasite, plant upon plant of glass ivy, bearing crystal bells, {181b} each of which, too, protrudes its living flower; on another leg is a fresh species, like a little heather-bush of whitest ivory, {182} and every needle leaf a polype cell—let us stop before the imagination grows dizzy with the contemplation of those myriads of beautiful atomies. And what is their use? Each living flower, each polype mouth is feeding fast, sweeping into itself, by the perpetual currents caused by the delicate fringes upon its rays (so minute these last, that their motion only betrays their presence), each tiniest atom of decaying matter in the surrounding water, to convert it, by some wondrous alchemy, into fresh cells and buds, and either build up a fresh branch in their thousand-tenanted tree, or form an egg-cell, from whence when ripe may issue, not a fixed zoophyte, but a free swimming animal. And in the meanwhile, among this animal forest grows a vegetable one of delicatest sea-weeds, green and brown and crimson, whose office is, by their everlasting breath, to reoxygenate the impure water, and render it fit once more to be breathed by the higher animals who swim or creep around. Mystery of mysteries! Let us jest no more,—Heaven forgive us if we have jested too much on so simple a matter as that poor spider-crab, taken out of the lobster-pots, and left to die at the bottom of the boat, because his more aristocratic cousins of the blue and purple armour will not enter the trap while he is within. I am not aware whether the surmise, that these tiny zoophytes help to purify the water by exhaling oxygen gas, has yet been verified. The infusorial animalcules do so, reversing the functions of animal life, and instead of evolving carbonic acid gas, as other animals do, evolve pure oxygen. So, at least, says Liebig, who states that he found a small piece of matchwood, just extinguished, burst out again into a flame on being immersed in the bubbles given out by these living atomies.