Chapter XXI: Part II (5)

Professor Clark also tried various experiments upon the common flat worm, or _planaria_, which may be found so readily in our ponds, creeping over stones and aquatic plants, and is so easily recognized by its opaque white color, and the liver-colored ramifications of its intestine. He cut the creature in two, and immediately after the operation the halves crawled away as if nothing had happened; the anterior part preceding an ideal tail, and the posterior one following an equally imaginary head and brain. He watched the pieces from day to day, and found that each reproduced its missing half by a slow process of budding and growth. This _planaria_ may be cut into several pieces, and each will reproduce what is requisite to complete the mangled organism. If the tail of a lizard be broken off, a {238} new one will grow; and crabs, lobsters, spiders, etc., are known to replace their amputated limbs. The instances we now and then meet with of what are called _monsters_--two-headed dogs, calves with six legs, and, more rarely, even double-headed human beings, are examples of the phenomenon of budding--which is very common, by the way, among fishes; and there is an animalcule called the _amoeba_ which shows a more remarkable tenacity of life than any of the other creatures we have mentioned, since you may divide and subdivide it until it is physically impossible to reduce it to particles any smaller, and yet each piece will live.

The discovery that animals may originate in so many ways independent of maternal gestation naturally suggests the inquiry whether further researches may not develop still other methods of reproduction, in which the new-born creature shall have no connection whatever with any previously existing individual. Thus we are brought back to the question which was thought to have been settled long ago, whether generation ever takes place spontaneously, as Aristotle and the old physicists supposed it did. Later naturalists, following the Italian, Redi, utterly rejected the supposition; but within the present century it has found many reputable supporters, and Professor Clark is one of them. When organic matter decays, numbers of _infusoria_, or microscopic plants and animals, arise in it. Where do they come from? Do the disorganized particles, set free by the process of decomposition, combine into new forms, which are then endowed with life by the direct action of Almighty power; or is the decaying substance merely the _nest_ in which minute eggs or seeds, borne thither upon the air, or dropped by insects, find conditions suitable for their development in the ordinary natural way? The question is not easily answered. Many of these germs are so excessively minute as to defy detection. Some of the infusoria are no larger than the twenty-four-thousandth of an inch in diameter, and it is estimated that a drop of water might contain five hundred millions of them. It is obvious that the germs of such little creatures must be invisible even with the best microscope. The problem can only be solved by placing a portion of the decomposing matter under such conditions that any germs it may contain shall infallibly be killed and that none can possibly reach it; then, if infusoria appear, we shall know that they have been generated spontaneously. The great difficulty is in securing these conditions. For the development of the living forms we require both water and air. How are we to be certain that there are no living germs in the organic matter before we begin the experiment? that there are none in the water? that none are brought by the air? The action of heat has been relied upon for the destruction of germs in the organic matter and the water, and it has been sought to purify the air from them by passing it through sulphuric add; but experience has shown that sulphuric add does not kill the germs; so of course experiments performed in that way prove nothing. Professor Clark quotes a series of very delicate experiments tried by Professor Jeffries Wyman, of Harvard University, which seem to us to come nearer to proving spontaneous generation than any others with which we are acquainted. He proceeded in three different methods, as follows:

1. The organic matter, consisting of a solution of beef or mutton juice (or, in a few instances, vegetable matter), was placed in a flask fitted with a cork through which passed a glass tube. The cork was pushed deeply into the mouth of the flask, and the space above it was filled with an adhesive cement, composed of resin, wax, and varnish. The tube was drawn to a narrow neck a little way above the cork, and bent at right angles, and {239} the end of it inserted in an iron tube, where it was secured by a cement of plaster of Paris. The rest of the iron tube was filled with wires, leaving only very narrow passages between them. The solution in the flask was then boiled--in some cases as long as two hours--in order to kill any germs which might be enclosed, and to expel the air. The iron tube and wires at the same time were heated to redness. When the boiling had continued long enough the heat was withdrawn from beneath the flask, and the steam was allowed slowly to condense. As it did so, air flowed in between the red-hot wires, which had been kept at a temperature high enough, it was supposed, to destroy any germs in the air that passed through them. The flask was then hermetically sealed by fusing the glass tube with the blow-pipe. When opened, several days afterward, it was found to contain animal life.

2. A similar solution was placed in a flask the neck of which, instead of being supplied with a cork and tube, was drawn out and bent at right angles, and then fitted to the iron tube containing wires. The experiment was performed as by method No. 1, and with the same result.

3. That there might be no suspicion of imperfectly sealed joints, a solution was put into a flask with a narrow neck, and the neck itself was then closed by fusing the glass. The whole flask was then immersed in boiling water. At the expiration of a few days living infusoria were found in two instances out of four.

Now these experiments undoubtedly prove that generation sometimes occurs spontaneously, provided it be true, as Professor Clark assumes, that there was no imperfection in the closing of the flasks (which we see no reason to doubt), and that the infusorial germs are destroyed by boiling. We confess that it is hard to believe they could have survived such a heat as was applied to them in these cases; but is it certain that they could not? A writer in an English review a few years ago, whom we believe to have been Mr. G. H. Lewes, announced that he had boiled certain germs _an hour and three-quarters_, and yet they remained perfectly unaltered. At most, therefore, we can regard spontaneous generation as a probable phenomenon.

Whether spontaneous generation, if it occurs at all, occurs by the formation of an egg from which the animalcule is hatched, or by the immediate formation of the adult, Professor Clark does not attempt to say; but the French naturalist M. Pouchet, who is one of the foremost advocates of the theory, holds that an egg is produced first. If this is true we shall have a striking correlative to the proposition with which we began this paper: not only can living creatures be developed where no egg has been deposited, but eggs can be produced where there is no animal to lay them. _Omne ovum e vivo_ will be no more true than _Omne vivum ex ovo._

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{240}

From Chambers's Journal

POOR AND RICH.

In a shattered old garret scarce roofed from the sky,
Near a window that shakes as the wind hurries by,
Without curtain to hinder the golden sun's shine,
Which reminds me of riches that never were mine--
I recline on a chair that is broken and old.
And enwrap my chilled limbs--now so aged and cold--
'Neath a shabby old coat, with the buttons all torn.
While I think of my youth that Time's footprints have worn.
And remember the comrades who've one and all fled,
And the dreams and the hopes that are dead with the dead.

But the cracked plastered walls are emblazoned and bright
With the dear blessed beams of the day's welcome light.
My old coat's a king's robe, my old chair is a throne,
And my thoughts are my courtiers that no king could own;
For the truths that they tell, as they whisper to me,
Are the echoes of pleasures that once used to be,
The glad throbbings of hearts that have now ceased to feel,
And the treasures of passions which Time cannot steal;
So, although I know well that my life is near spent,
Though I'll die without sorrow, I live with content.

Though my children's soft voices no music now lend;
Without wife's sweet embraces, or glance of a friend;
Yet my soul sees them still, as it peoples the air
With the spirits who crowd round my broken old chair.
If no wealth I have hoarded to trouble mine ease,
I admit that I doted on gems rich as these;
And when death snatched the casket that held each fair prize,
It flew to my heart where it happily lies;
So, 'tis there that the utt'rings of love now are said
By those dear ones, whom all but myself fancy dead.

So, though fetid the air of my poor room may be.
It still has all the odors of Eden for me.
For my Eve wanders here, and my cherubs here sing,
As though tempting my spirit like theirs to take wing.
Though my pillow be hard, where so well could I rest
As on that on which Amy's fair head has been pressed?
So let riches and honor feed Mammon's vain heart,
From my shattered old lodging I'll not wish to part;
And no coat shall I need save the one I've long worn.
Till the last thread be snapped, and the last rent be torn.

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{241}

From The Lamp.

ALL-HALLOW EVE; OR, THE TEST OF FUTURITY.

BY ROBERT CURTIS.

[CONCLUSION.]