I am aware that this is not easily to be reconciled with M. Doyère’s experiments, since the application of a temperature so high as 300° Fahr. (nearly a hundred degrees above boiling water) must, one would imagine, have completely desiccated the animals, in spite of any amount of protecting dirt. It is possible that M. Doyère may have mistaken that previously-noted swelling-up of the bodies, on the application of water, for a return to vital activity. If not, I am at a loss to explain the contradiction; for certainly in my experience a much more moderate desiccation—namely, that obtained by simple evaporation over a mantelpiece, or under a large bell-glass—_always_ destroyed the animals, if little or no dirt were present. The subject has recently been brought before the French Academy of Sciences by M. Davaine, whose experiments[13] lead him to the conclusion that those Rotifers which habitually live in ponds will not revive after desiccation: whereas those which live in moss always do so. I believe the explanation to be this: the Rotifers living in ponds are dried without any protecting dirt, or moss, and that is the reason they do not revive. After having satisfied myself on this point, I did what perhaps would have saved me some trouble if thought of before. I took down Spallanzani, and read his account of his celebrated experiments. To my surprise and satisfaction, it appeared that he had accurately observed the same facts, but curiously missed their real significance. Nothing can be plainer than the following passage: “But there is one condition indispensable to the resurrection of wheel-animals: it is absolutely necessary that there should be a certain quantity of sand; without it they will not revive. One day I had two wheel-animals traversing a drop of water about to evaporate, which contained very little sand. Three quarters of an hour after evaporation, they were dry and motionless. I moistened them with water to revive them; but in vain, notwithstanding that they were immersed in water many hours. Their members swelled to thrice the original size, but they remained motionless. To ascertain whether the fact was accidental, I spread a portion of sand, containing animals, on a glass slide, and waited till it became dry in order to wet it anew. The sand was carelessly scattered on the glass, so as to be a thin covering on some parts, and on others in a very small quantity: here the animals did not revive: but all that were in those parts with abundance of sand revived.”[14] He further says that if sand be spread out in considerable quantities in some places, much less in others, and very little in the rest, on moistening it the revived animals will be numerous in the first, less numerous in the second, and none at all in the third.