《自然史（第3卷）》：

　　By the experiments we have just described, I was assured that females,as well as males, have a seminalliquor which contains moving substances; that these substances were not real animals, but only living organic particles; and that those particles exist, not only in the seminal liquors of the two sexes, but even in the flesh of animals, and in the germs of vegetables. To discover whether all the parts of animals, and all the germs of vegetables, contained living organic particles, I caused infusions of the flesh of different animals to be made, and of more than twenty kinds of seeds of different plants; and after they had infused four or five days, in phials closely stopt up, I had the satisfaction to see moving organic parts in them all; some appeared sooner, and others later; some preserved their motion for months together, while others were soon deprived ofit; some directly produced large moving globules, that had the appearance of real animals, which changed their figures, separated, and became successively smaller: others produced only small globules, whose motions were very brisk; others produced filaments which lengthened and seemed to vegetate, swelled, and afterwards thousands of moving globules issued therefrom; but it is useless to detail my observations on the infusion of plants, since Mr. Needham has published so excellent a treatise on the subject. I read the preceding treatise to that able naturalist, and often reasoned with him on the subject, particularly on the probability that the germs of vegetables contained similar moving bodies to those in the seed of male and female animals. He thought those views sufficiently founded to deserve to be pursued; and therefore began to make experiments on all parts of vegetables; and I must own that the ideas I gave him on this subject have reaped greater profit under his hands than they would have done from me. I could quote many examples, but shall confine myself to one, because I indicated the circumstance I am going to relate.

　　To determine whether the moving substances seen in the infusions of flesh were true animals, or only, as I supposed, moving organic particles, Mr. Needham imagined that he had only to examine some roasted meat, because if they were animals the fire must destroy them; and if not animals, they might still be found there as well as when the meat was raw; having therefore taken the jelly of veal, and other roasted meat, he infused them for several days in water, closely corked up in phials, and upon examination he found in every one of them a great quantity of moving substances. He shewed me some of these infusions, and among the rest that of the jelly of veal, in which there were moving substances, perfectly like those in the seminal liquor of a man, a dog, and a bitch, when they have no threads, or tails; and although we perceived them to change their figures, their motions so perfectly resembled those of an animal which swims, that whoever saw them, without being acquainted with what has been already mentioned, might certainly have taken them for real animals. I shall only add, that Mr. Needham assured himself, by a multiplicity of experiments, that all parts of vegetables contain moving organic particles, which confirms what I have saidi and extends my theory on the composition of organized beings, and their reproduction.

　　All animals, both male and female, and all vegetables whatsoever, it is therefore evident are composed of living organic parts. These organic parts are in the greatest abundance in the seminal liquor of animals, and in seeds of vegetables. It is from the union of these organic parts returned from all parts of the animal or vegetable body, that reproduction is performed, and is always like the animal or vegetable in which it operates; because the union of these organic parts cannot be made but by the means of an internal mould, in which the form of an animal or vegetable is produced. It is in this also the essence of the unity and continuity of the species consists, and will so continue while the great Creator permits their existence.

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