life, free and oviparous.

This observation leads us to another sexual singularity, lately observed, of males and females of different kinds in one and the same species, and which give birth to progeny which do not resemble each other; the same animals, or rather the same species, proceed from two different eggs fecundated by different spermatozoids.

Now that these transmigrations are perfectly known and admitted, the starting-point of the inquiry has been so entirely forgotten that the honour of the discovery has been frequently attributed to fellow-workers, who had no knowledge of it till the demonstration had been completed, and the new interpretation generally accepted. But let us return to our subject.

The assistance rendered by animals to each other is as varied as that which is found amongst men. Some receive merely an abode, others nourishment, others again food and shelter; we find a perfect system of board and lodging combined with philozoic institutions arranged in the most perfect manner. But if we see by the side of these paupers, some which render to one another mutual services, it would be but little flattering to them to call all indiscriminately either parasites or messmates (commensaux). We think that we should be more just to them if we designated the latter kinds mutualists, and thus mutuality will take its place by the side of mess-table arrangements (commensalism) and of parasitism.

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-bœuf 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-bœuf (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 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 categories.

But whence come those disgusting beings, whose name alone inspires us with horror, and which instal themselves without ceremony, not in our dwellings, but in our organs, and which we find it more difficult to expel than rats or mice? They all derive their existence from their parents.

The time has passed when a vitiated condition of the humours, or the deterioration of the parenchyma was considered a sufficient cause for the formation of parasites, and when their presence was regarded as an extraordinary phenomenon resulting from the morbid dispositions of the organism. We have reason to hope that this language will, during the next generation, have entirely disappeared from works on physiology and pathology. Neither the temperament nor the humours have any influence on parasites, and they are not more abundant in delicate individuals than in those who enjoy the most robust health. On the contrary, all wild animals harbour their parasitical worms, and the greater part of them have not lived long in captivity, before nematode and cestode worms completely disappear. It is only the imprisoned parasites which do not desert them.

All these mutual adaptations are pre-arranged, and as far as we are concerned, we cannot divest ourselves of the idea that the earth has been prepared successively for plants, animals, and man. When God first elaborated matter, He had evidently that being in view who was intended at some future day to raise his thoughts to Him, and do Him homage.

This is the answer which I would give to the question recently propounded by Mons. L. Agassiz. “Were the physical changes to which our globe has been subjected effected for the sake of the animal world, considered in its relations from the very beginning, or are the modifications of animals the result of physical changes?” in other words, has the earth been made and prepared for living beings, or have living beings been as highly developed as was possible, according to the physical vicissitudes of the planet which they inhabit?

This question has always been discussed, and that science which cannot look beyond its scalpel, will never succeed in resolving it. Each one must seek by his own reason the solution of the great problem.

When we see the newly-born colt eagerly seeking for its mother’s teats, the chick as soon as it is hatched beginning to peck, or the duckling seeking its puddle of water, can we recognize anything but instinct as the cause of these actions, and is not this instinct the libretto written by Him who has forgotten nothing?

The statuary who tempers the clay from which to make his model, has already conceived in his mind the statue which he is about to produce. Thus it is with the Supreme Artist. His plan for all eternity is present to His thought. He will execute the work in one day, or in a thousand ages. Time is nothing to Him; the work is conceived, it is created, and each of its parts is only the realization of the creative thought, and its predetermined development in time and space.

“The more we advance in the study of nature,” says Oswald Heer in “Le Monde primitif” which he has just published, “the more profound also is our conviction, that belief in an Almighty