" The next day- I saw three particular ani malcula swimming through the vvater, the smallest of which was 100 times smaller than the above said animalcula.
" Now, ought we not to be astonished to find that these small insects can lie twenty-one months dry, and yet live, and as soon as ever they are put into water fall a swimming, or fastening the hinder parts of their bodies to the glass, and then produce the wheels, just as if they had never wanted water. In the month of September I put a great many of the last mentioned animals into a wide glass tube, which placed themselves on the sides of the glass presently, whereupon I poured the water out, and then observed that several animal cula, to the number of eighteen or nineteen, lay by one another in the space of a coarse sand, all which, when there remained no more water, closed up themselves in a globular figure.
" Some of the bodies of these animalcula were so strongly dried up, that one could see the wrinkles in them, and they were of a reddish colour ; a few others were so trans parent, that if you held them up between your eye and the light, you might move your fingers behind them, and see the motion through their bodies.
" After that these animalcula had lain thus dried up a day or two, I invited some gentle men to come and partake of the agreeable spectacle with me, that is, to see how the said animalcula would divest themselves of their globular figure, and swim about in the water. According to which, after my friends had satisfied their curiosity in viewing the animal cula in their oval or globular form, some of which were so pellucid as if they had been little glass balls, I poured some water into the glass tube, whereupon they presently sunk to the bottom, and then the gentlemen took the said tube into their hands, and viewing it one after another through a microscope, they saw the animalcula, after the space of about half an hour, beginning to open and extend their bodies, and getting clear of the glass to swim about the water, excepting only two of the largest of them, that stayed longer on the sides of the glass before they stretched out their bodies and swam away." Since the period that Leeuwenhoek made these observations, this subject has been one of great interest to naturalists ; and a question has been raised as to the condition of the dried animalcules. Leeuwenhoek seems first to have raised this question, by declaring that complete desiccation must involve the death of an animal, and as it could not come to life after once dead, that the revivified animalcules were not completely desiccated. The experi tnents of Leeuwenhoek were repeated by other observers, and the same results obtained. Needham not only saw it in the Rotifers, but also in the Vibrio of blighted wheat. Ilis opi nion was, that the desiccation was quite com plete. Needham's experiments were repeated by Baker, who also came to the same conclu sion. These observers were followed by Spallanzani, who, in a most elaborate series of investigations, confirmed the conclusions at which Needham and Baker had arrived. He, however, points out the fact, that the re vivification of the animalcules was much more constant when they were dried with sand than when dried on a smooth surface. He found also that animalcules when in this desiccated state would bear a much greater heat, as well as a much more intense degree of cold, than when in an active state. Animalcules that, whilst living, would not beara higher temperatare than 100° Fahr., when dried were resuscitated after having been exposed to a temperature of 144° Fahr. They also recovered after being ex posed to a degree of cold 24° cent. below zero. Although numerous facts of the same kind were recorded by. subsequent observers, the accuracy of these observations have been doubted by several eminent naturalists, at the head of whom stands Bory St. Vincent, who, in the article Roliferes, in the Dictionnaire Classique d'Histoire Naturelle, says, that the desiccated animals have not been resuscitated at all, but that they are developed from eggs, in the same way as the Daphnia and other minute entomostracous crustacea are de veloped after the first shower of rain which falls on the soil in which their ova are con tained. The correctness of these observations
can now hardly be doubted ; and since the time that Bory St. Vincent wrote, a great number of observers of undoubted accuracy, have repeated the experiments of Spallanzani and others, and have arrived at the same con. elusions. Doyere, a French naturalist, pub lished a very extended series of investigations on this subject, in the Annales des Sciences Naturelles for 1842, in which various species of animalcules were perfectly desiccated and resuscitated under circumstances which would entirely prevent the supposition of a develop ment such as was suggested by Bory St. Vincent. Experiments of the same kind have been performed by observers in our own country. Dr. Carpenter says, " In the sum mer of' 1835, I placed a drop of water con taining a dozen specimens of the Rotifer vulgaris on a slip of glass, and allowed the water to dry up, which it did speedily., the weather being hot. On the next day I ex amined the glass under the microscope, and observed the remains of the animals coiled up into circles ; a form which they not unfre. quently assume when alive, but so perfectly dry that they would have splintered in pieces if touched with the point of a needle, as I had observed before in similar experiments. I covered them with another drop of water, and in a few minutes ten of them had revived, and these speedily began to execute all their regular movements with activity and energy. After they had remained alive for a few hours, I again allowed the water which covered them to dry up, and I reviewed it on the following day with the same result. This process I re peated six times ; on each occasion one or two of the animals did not recover, hut two sur vived to the last, and with these I should have experimented again had I not acciden tally lost them." Professor Owen in his Lectures, after alluding to the experiments of Professor Schulze on this subject, says, " I myself wit nessed at Freiburg, in 1838, the revival of an Arctiscon, which had been preserved in dry sand by the professor upwards of four years." We must, however, quote one great authority against the view that a perfect desiccation of the resuscitated animals has ever taken place, and that is Professor Ehrenberg him self. He does not go so far as Bory St. Vincent, but regards the desiccation spoken of as an assumption, and supposes that the rotiferous and other animalcules which are re vivified have the power of living in both water and air; although they do not perform their functions so actively in the latter, yet that they still perform them. He says that he has seen the stomachs of' Rotifera filled with granules of a conferva which was growing in the sand in which they were supposed to have been desic cated. Although we feel that the opinions of Ehrenberg on the subject of animalcules are en titled to great respect, we think that he has not investigated this subject with the candour that would entitle his conclusions to confidence. There is no a priori evidence why a perfect desiccation and suspension of the functions of life should not take place. This is the natu ral condition of the embryo of the seeds of many plants, which, after hundreds of years, when placed in proper circumstances, will exhibit all the functions of vegetable life. Amongst the highest forms of animals we often witness a suspension of the functions under special external circumstances, which, although not amounting to the extent found amongst the Infusoria, would yet prepare us to admit a far more intense degree of the same phenomenon amongst those beings in which animality was less decided, and the vegetative functions more predominant. There is no necessity to regard the condition of desicca tion in which those animals may be placed as one of death. The conditions of the exist ence of the vitality of the animal, whatever they may be, are undoubtedly secured in this state, and thd conditions of the activity of this vitality are alone withdrawn.