I will not dwell on these; though, if I were writing a book of pure science, there is a wondrous array of facts of the most striking and interesting character, connected with the structure, the metamorphoses, and the habits, of the Entozoic Worms, which I might present to my readers. It is more pleasant to consider other facts, perhaps not less marvellous, which, as they do not come quite so home to our personal feelings, will not excite horror and disgust in our minds. The _economy_ of creation is remarkable. He who, by His divine manipulation converted five loaves and two small fishes into a hearty meal for five thousand men, besides women and children, and who could, with the same ease have made them a hundred times as much, said, when the meal was over, "Gather up the fragments, that nothing be lost." And, when He spread the earth with life, though His resources were infinite, He ordained that one object, itself healthfully enjoying life, and fulfilling its own proper ends of being, should be a microcosm, on which another range of life should find its sphere, and on which it should disport, as on an independent world. I have often admired, in the gorgeous tropical forests, what a wilderness of vegetation a single tree supports; what numbers of orchids and wild pines spring out of the forks, what creepers and lianes hang and twine about its branches, what elegant ferns cluster on the horizontal limbs, what snake-like cacti creep from bough to bough, what mosses, and jungermanniæ crowd in every crevice, what many-coloured lichens stud the rugged bark! And then animal life is swarming in all this great field of parasitic vegetation. Reptiles and birds, snails and slugs, insects and millepedes, and spiders and worms nestle by thousands in such prolific situations, so that a great old tropical tree, one of the giant figs or cotton-trees, is a very museum in itself. And in my wanderings along the sea-edge here at home how often have I been amazed at the diverse population, plant and animal, which crowds a single oar-weed, or tangle! The stem fringed with delicate red-weeds, as the minute _Rhodymeniæ_, and _Polysyphoniæ_, and _Callithamnia_; the tortuous roots studded with Anemones, with _Flustræ_ and _Lepraliæ_, and multitudes of other _Polyzoa_, with tiny Polypes of many kinds, with Barnacles and Limpets, and sheltering small Crustacea, and Mites, and Annelids by scores.