This is very marvellous: so marvellous that a mind, trained in the cultivated caution of science, will demand the evidence on which it is based. Two months ago I should have dismissed the doubt with the assurance that the evidence was ample and rigorous, and the fact indisputable. For not only had the fact been confirmed by the united experience of several investigators: it had stood the test of very severe experiment. Thus in 1842, M. Doyère published experiments which seemed to place it beyond scepticism. Under the air-pump he set some moss, together with vessels containing sulphuric acid, which would absorb every trace of moisture. After leaving the moss thus for a week, he removed it into an oven, the temperature of which was raised to 300° Fahrenheit. Yet even this treatment did not prevent the animals from resuscitating when water was added. In presence of testimony like this, doubt will seem next to impossible. Nevertheless, my own experiments leave me no choice but to doubt. Not having witnessed M. Doyère’s experiment, I am not prepared to say wherein its fallacy lies; but that there _is_ a fallacy, seems to me capable of decisive proof. In M. Pouchet’s recent work[11] I first read a distinct denial of the pretended resuscitation of the Rotifers; this denial was the more startling to me, because I had myself often witnessed the reawakening of these dried animals. Nevertheless, whenever a doubt is fairly started, we have not done justice to it until we have brought it to the test of experiment; accordingly I tested this, and quickly came upon what seems to me the source of the general misconception. Day after day experiments were repeated, varied, and controlled, and with results so unvarying that hesitation vanished; and as some of these experiments are of extreme simplicity, you may verify what I say with little trouble. Squeeze a drop from the moss, taking care that there is scarcely any dirt in it; and, having ascertained that it contains Rotifers, or Tardigrades,[12] alive and moving, place the glass-slide under a bell-glass, to shield it from currents of air, and there allow the water to evaporate slowly, but completely, by means of chloride of calcium, or sulphuric acid, placed under the bell-glass; or, what is still simpler, place a slide with the live animals on the mantelpiece when a fire is burning in the grate. If on the day following you examine this perfectly dry glass, you will see the contracted bodies of the Rotifers, presenting the aspect of yellowish oval bodies; but attempt to resuscitate them by the addition of a little fresh water, and you will find that they do not revive, as they revived when dried in the moss: they sometimes swell a little, and elongate themselves, and you imagine this is a commencement of resuscitation; but continue watching for two or three days, and you will find it goes no further. Never do these oval bodies become active crawling Rotifers; never do they expand their wheels, and set the