But in order to leave this matter as little in doubt as possible, let us examine other substances. Can it be said, the active machines which Mr. Needham perceived in the milt of the calmar were animals? Can it be thought that eggs, which are active machines of another kind, are also animals? If we turn our eyes to the representation of almost all the moving bodies Leeuwenhoek saw in different matters, shall we not be convinced, even at the first inspection, that those bodies are not animals, since not one of them has any limbs, but are all either globular or oval? If we afterwards examine what this celebrated naturalist says, when he describes the motion of these pretended animals, we can no longer doubt of his being in an error when he considered them as such; and we shall be still more and more confirmed that they are only moving organic particles by the following examples: Leeuwenhoek gives[W] the figure of the moving bodies which he observed in the liquor of a male frog. This figure only represents a slender body, long, and pointed at one of its extremities; and of this he says, "Uno tempore caput (thus he calls the thickest extremity of this moving body) crassius mihi apparebat alio; plerumque agnoscebam animalculum haud ulterius quam a capite ad medium corpus, ob caudæ tenuitatem, & cum idem animalculum paulo vehementius moveretur (quod tamen tarde fiebat) quasi volumine quodam circa caput ferebatur. Corpus fere carebat motu; cauda tamen in tres quatuorve flexus volvebatur." This then is the change of form which I mentioned to have seen, the mucilage from which the moving bodies use all their efforts to be disengaged, the slowness of their motion before they are disengaged; and the animal, according to Leeuwenhoek, one part of which is in motion, and the other dead: for he afterwards says, "Movebant posteriorem solum partem, quæ ultima, morti vicinia esse judicabam." All this does not agree with an animal, but with what I have spoken of; excepting that I never saw the tail move but by the agitation of the body. He afterwards says, speaking of the seminal liquor of a cod, "Non est putandum omnia animalcula in semine aselli contenta uno eodemque tempore vivere, sed illa potius tantum vivere quæ exitui seu partui viciniora sunt, quæ & copiosiori humido innatant præ reliquis vita carentibus, adhuc in crassa materia, quam humor eorum efficit, jacentibus." [W] Vol. I. p. 51.