It would also be necessary to coin another name for those which, like certain crustaceans, or even some birds, are rather guests which _smell out a feast from afar_ (pique-assiettes) than parasites; and for others which repay by an ill turn the assistance which they have received. And what name shall we give to those which, like the plover, render services which may be compared to medical attendance? This bird in fact performs the office of dentist to the crocodile. A small species of toad acts as an accoucheur to his female companion, making use of his fingers as a forceps to bring the eggs into the world. Again, the pique-boeuf performs a surgical operation, each time that he opens with his lancet the tumour which encloses a larva in the midst of the buffalo's back. Nearer home, we see the starling render in our own meadows the same service as the pique-boeuf (_Buphaga_) in Africa; and we may see that among these living creatures there is more than one speciality in the healing art. We must not forget that the occupation of a gravedigger is equally xxv general in nature, and that it is never without some profit to himself or his progeny that this gloomy workman inters the bodies of the dead. Certain animals have an occupation analogous to that of the shoeblack or the scourer, and they freshen up with care, and even with a kind of coquettish pleasure, the toilet of their neighbours. And how must we designate the birds known by the name of stercorariæ, which take advantage of the cowardice of sea-gulls in order to live in idleness? It is useless for the gulls to trust to the strength of their wings, the stercorariæ in the end compel them to disgorge their food in order that they may partake of the spoils of their fishery. When followed up too closely, these timid birds throw up the contents of their crop, to render themselves lighter, like the smuggler who finds no means of safety except in abandoning his load. We must not, however, be too hard upon all this class, since very often, as in the case of the gnat, it is only one of the sexes which seeks a victim. All animals usually live for the passing day; and yet there are some which practise economy, which are not ignorant of the advantages of the savings bank, and, like the raven and the magpie, think of the morrow, to lay up in store the superfluity of the day's provision. As we have before said, this little world is not always easy to be known, and in its societies, to which each brings his capital, some in activity, others in violence or in stratagem, we find more than one _Robert Macaire_ who contributes nothing, and takes advantage of all. Every species of animal may have its parasites and its messmates, and each may perhaps have some of different sorts, and in diverse xxvi categories.