This section is from the book "A Library Of Wonders And Curiosities Found In Nature And Art, Science And Literature", by I. Platt. Also available from Amazon: A library of wonders and curiosities.
The preceding article is naturally followed by reproduction. Reproduction is usually understood to mean the restoration of a thing before existing, and since destroyed.
It is very well known that trees and plants may be raised from slips and cuttings; and some late observations have shown, that there are some animals which have nearly the same property. The polype (See Hydra) was the first instance we had of this kind; but we had scarcely time to wonder at the discovery M. Trembley had made, when M Bonnet discovered the same property in a species of water-worm. Amongst the plants which may be raised from cuttings, there are some which seem to possess this quality in so eminent a degree, that the smallest portion of them will become a complete tree again. A twig of willow, poplar, or many other trees, being planted in the earth, takes root, and becomes a tree, every piece of which will in the same manner produce other trees. The case is the same with these worms: they are cut to pieces, and these several pieces become perfect animals; and each of these may be again cut into a number of pieces, each of which will in the same manner produce an animal. It has been supposed by some, that these worms were oviparous; but, M. Bonnet, on cutting one on them to pieces, having observed a slender substance, resembling a small filament, to move at the end of one of the pieces, separated it, and on examining it with glasses, found it to be a perfect worm, of the same form with its parent, which lived and grew larger in a vessel of water into which he put it. These small bodies are easily divided, and very readily complete themselves again, a day usually serving for the production of a head to the part that wants one; and, in general, the smaller and more slender the worms are, the sooner they complete themselves after this operation. When the bodies of the large worms are examined by the microscope, it is very easy to see the appearance of the young worms alive, and moving about within them; but it requires great precision and exactness to be certain of this, since the ramifications of the great artery have very much the appearance of young worms, and they are kept in a sort of continual motion by the svstoles and diastoles of the several portions of the artery, which serve as so many hearts. It is very certain, that what we force in regard to these animals by our operations, is done also naturally every day in the brooks and ditches where they live. A curious observer will find in these places many of them without heads or tails, and some without either; as also, other fragments of various kinds, all of which are in the act of completing themselves; but whether accidents have reduced them to this state, or they thus purposely throw off parts of their own bodies for the production of more animals, it is not easy to determine. They are plainly liable to many accidents, by which they lose the several parts of their bodies; and they must perish very early, if they had not a power of reproducing what was lost. They are often broken into two parts, by the resistance of some hard piece of mud which they enter; and they are subject to a disease, a kind of gangrene, rotting off the several parts of their bodies, by which they must inevitably perish, were they not possessed of this surprising property.
The reproduction of several parts of lobsters, crabs, etc.:is one of the greatest curiosities in natural history. It seems, indeed, inconsistent with the modern philosophical system of generation, which supposes the animal to be wholly formed in the egg; that, in lieu of an organical part of an animal cut off, another should arise perfectly like it: the fact, however, is too well attested to be denied. The legs of lobsters, etc. consist each of five articulations; now, when any of the legs happen to break by any accident, as by walking, etc. which frequently occurs, the fracture is always found to be at the suture near the fourth articulation; and what they thus lose is exactly reproduced in some time afterwards; that is, a part of the leg shoots out, consisting of four articulations, the first whereof has two claws, as before; so that the loss is entirely repaired.
If the leg of a lobster be broken off by design at the fourth or fifth articulation, what is thus broken off is always reproduced, even after a second or third accident. But if the fracture be made in the first, second, or third articulation, the reproduction is not so certain. And it is very surprising, that if the fracture be made at these articulations, at the end of two or three days, all the other articulations are generally found broken off to the fourth, which, it is supposed, is done by the creature itself, to make the reproduction certain. The part reproduced, is not only perfectly similar in form to that retrenched, but also, in a certain space of time, it grows equal to it. The creature is, however, frequently taken before this is accomplished. Hence it is that we frequently see lobsters, which have their two large legs unequal in all proportions.