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 16 Persius. I may walk on, but the sight has sent a slight electric shock through me. Why, sir, there is more to me in the tail of one of those tadpoles than in all the poems of that obscure and dreary Persius. But I won’t thrash your Jew unless you thrash mine.”

“Why, what on earth can you do with the tail?”

“Do with it? Study it, experiment on it, put it under the microscope, and day by day watch the growth of its various parts. At first it is little but a mass of cells. Then I observe some of these cells assuming a well-known shape, and forming rudimentary blood-vessels. I also observe some other cells changing into blood-cells. Then the trace of muscles becomes visible. These grow and grow, and the pigment-cells, which give their colour to the tail, assume fantastic shapes.”

“Very interesting, I dare say."

“You don’t seem to think so, by your tone. But look in this vase: here you see several tadpoles with the most apologetic of tails—mere stumps, in fact. I cut them off nine days ago."

"Will they grow again?"

"Perfectly; because, although the hog dispenses with a tail, and gradually loses it by a process of resorption as he reaches the frog form, the tadpole needs his tail to swim with; and Nature kindly supplies any accident that may deprive him of it.”

"Yes, yes," added Gerunds, glad to feel himself once more in the region of things familiarly known: “just like the lobster, or the crab, you know. They tear off their legs and arms in the most reckless manner, yet always grow them again."

"And would you like to know what has become of these tails?”

"Arn't they dead?"

“Not at all. ‘Alive and kicking. ”

“Alive after nine days? Oh! oh!"

“Here they are in this glass. It is exactly nine days since they were cut off, and I have been watching them daily under the microscope. I assure you that I have seen them grow, not larger, indeed, but develope more and more, muscle-fibres appearing where no trace of fibre existed, and a cicatrice forming at the cut end.”

“Come, now, you are trying my gullibility!”

“I am perfectly serious. The discovery is none of mine. It was made this time last year by M. Vulpian in Paris, and I have only waited for the tadpole season to repeat the observations. He says that the tails constantly lived many days—as many as eighteen on one occasion; but I have never kept mine alive more than eleven. He says, moreover, that they not only grow, as I have said, but manifest sensibility, for they twist about with a rapid swimming movement when irritated. I have not seen this; but M. Vulpian is too experienced a physiologist to have been mistaken; and with regard to the growth of the tails, his observations are all the more trustworthy because he daily made drawings of the aspect presented by the tails, and could thus compare the progress made.”

“Well, but I say, how the deuce could they live when separated from the body? our arms or legs don‘t live; the lobster’s legs don‘t live.”

“Quite true; but in these cases we have limbs of a complex organisation, which require a complex

apparatus for their maintenance; they must have blood, the blood must circulate, the blood must be oxygenated—”

“Stop, stop; I don’t want to understand why our arms can’t live apart from our bodies. They don’t. The fact is enough for me. I want to know why the tail of a tadpole can live apart from the body.”

“It can. Is not the fact enough for you in that case also? Well, I was going to tell you the reason. The tail will only live apart from the body so long as it retains its early immature form; that is to say, so long as it has not become highly organised. If you cut it off from a tadpole which is old enough to have lost its external gills a week or more, the tail will not live more than three or four days. And every tail will die as soon as it reaches the point in its development which requires the circulation of the blood as a necessary condition.”

“But where does it get food?”

“That is more than I can say. I don’t know that it wants food. The power of abstinence possessed by reptiles is amazing. I was reading the other day an account of a reptile which had been kept in the Boston Museum eight-and-twenty months without any food, except such as it might have found in the small quantity of dirty water in which it was kept.”

“Really I begin to think there is more in these little beasts than I suspected. But you see it requires a deal of study to get at those things.”

“Not more than to get at any of the other open secrets of Nature. But since you are interested, look at these tails as the tadpoles come bobbing against? the side of the glass. Do you see how they are covered with little white spots?”

“No.”

“Look closer. All over the tail there are tiny cotton-er spots. Take a lens if your unaccustomed eye isn’t sharp enough. There, now you see them.”

“Yes; I see a sort of fluff scattered about.”

“That fluff is an immense colony of parasites. Let us place the tadpole under the microscope, and you will see each spot turn out to be a multitude of elegant and active animals, having bodies not unlike a crystal goblet supported on an extremely long and flexible stem, and having round their rim or mouth a range of long delicate hairs, the incessant motion of which gives a wheel-like aspect, and makes an eddy in the water which brings food to the animal.”

“Upon my word this is really interesting! How active they are! How they shrink up, and then, unwinding their twisted stems, expand again! What’s the name of this thing?”

“Vorticella. It may be found growing on water-fleas, plants, decayed wood, or these tadpoles. People who study the animalcules are very fond of this Vorticella.”

“Well, I never could have believed such a patch of fluff could tum out a sight like this: I could watch it for an hour. But what are those small yellowish things sticking on the side of these parasites?”

“Those, my dear Gerunds, are also parasites.”

“What, parasites living on parasites?”

“Why not? Nature is economical. Don’t you live on beef and mutton and fish? don’t these beefs,