In the manner I suppose all land to have been first brought to light, many islands have been produced in our own time. What was under the water is forced above it. The marine substances on the surface by degrees decay; moss appears, grass succeeds, then the smaller kind of plants, bushes and trees. Animal life begins and goes on upon the same scale from the minuter, to beings of more consequence. This system is at least as general as the other, but like that must be received with many restrictions; for it is certain that by far the greater part of vegetables and animals would never be found self-produced in any one place, tho’ many might live, and indeed flourish, if brought there.
Let us proceed from reasoning to facts. Some voyager discovers an island evidently formed by a vulcano, and very remote from other countries; it is a perfect wood to the water’s edge, has some plants which exist no where but in that spot, together with others common to places in the same latitude. It is full of insects, reptiles, birds, and sometimes quadrupeds. Now, if _every one_ of these organized bodies was not brought there, something must be self-produced.
In some islands of the East-Indies are serpents of an enormous size; who could carry them there? In all streams there are fish—how could they get there? Not from the sea, for fish which inhabit the source of rivers are as soon killed by salt water as in air, besides there are many rivers which do not run into the ocean. Perhaps this circumstance was never sufficiently considered. Every set of rivers is perfectly distinct from any other set. The greater number have some fish which exist no where but in the particular stream they are bred. Find any other cause for their first production than what must be taken from the old philosophy.
Let us attend to what we have always near us. Fill a vessel with water from the pump: it is pure, and contains neither animal, nor vegetable. After standing some days, a green substance begins to be formed in it, and which is inhabited by myriads of little beings: this seems the first step towards plants and animals. We are told indeed that the animalcules are from eggs laid by flies, and the green slime is a plant which has its proper seed. That the water may accidentally receive both eggs and seeds is highly probable; but these (by reasoning from other instances) seem the first efforts towards vegetable and animal life. Besides, it yet remains to be proved, that the air so abounds with flying seeds and insects. If the air swarmed, as is supposed, vision would be obstructed (as by a fog which consists of particles inconceivably small), and perhaps life in the nobler animals destroyed. The slime to be produced from seed then must have come from some of the same sort in the neighbourhood; besides, if its being produced in the water depended upon accident, which it does by this supposition, it must sometimes fail. Again, if the animals and vegetables, in the above instance, were from eggs floating in the air, why are the smallest always produced first? must it not sometimes happen that ova of a larger sort precede the smaller? which is never the case: not to mention the total impossibility of some ova, particularly of animals, being so conveyed.