XLVI
Little Monsters

One usually thinks of monsters as large. They are always, I believe, large and horrible in the fairy stories—giants and ogres and dragons and winged horses and chimeras and three-headed dogs and I don’t know what else, all most extraordinary to imagine as well as nice and creepy to read about. Really, however, there is no reason whatever why a monster should be large. It must be horrid, or unusual, or misshapen, or quite out of the ordinary. Then it is a true and proper monster, no matter how small it is. And as a matter of fact, some monsters, as strange as any maker of fairy stories ever invented, are too small to be seen at all, unless one looks for them with a microscope.

The planarian worms that I have just been telling about are monsters. If a two-headed calf is a monster, that people who go to the circus will pay to see, then surely a planarian is a still greater monster, with one extra head in the small of its back, another on the side of its tail, and four or five more hanging on at various places anywhere over its body; and this to say nothing of as many superfluous tails stuck on anywhere between. You know already that these monstrous planarians are formed because the worm, instead of healing up a cut as he should, seems possessed to grow a new head or tail out of it. I am going to tell you now how certain other strange monsters come to be.

You remember that earlier in this book, almost in fact, at the very first, I told you about how the eggs of all animals are, to begin with, single cells; and how afterwards, when they begin to grow, they split, first into two cells, then into four, then into eight, and so on, until finally, the single cell of the egg has become the hundreds and thousands which build the young animal.

Some of these eggs, especially those of certain of the small sea creatures such as star-fish and sea-urchins and the like, are extraordinarily tough. Indeed they have to be, else few of them would ever live to grow up at all. It is quite possible to take these eggs when the single cell has divided into two, and shake these two apart into two separate half eggs. You might think that each half egg would form a half animal. Instead, much like the planarian cut in halves, it forms a whole animal, half size.

Or we can wait till there are four cells, and shake these apart. Then we get four complete creatures, each quarter size. Or we can in the same way make eight. Beyond that we cannot go. Eight animals out of what was intended for one is all that egg can manage.

On the other hand, it is possible to take a half dozen eggs, which ought properly to have made as many separate creatures, and make them stick together into one gigantic egg, from which will hatch out a single gigantic animal, as large as the six or eight together which ought to have come from six or eight eggs.

Other strange things happen when the eggs, instead of growing in ordinary sea water, are put into water which has just a little bit more or less of something in it. For common sea water contains some half dozen different kinds of salt besides the one kind that people get out and use on the table and for cooking; and more or less of any one of these makes a salt water which is not quite the same as the salt water of the ocean. In fact, you must have noticed that salt water made with ordinary table salt does not taste by any means the same as ocean water.

[Accidents to growing fish eggs result in all sorts of double monsters.]