It must be observed that this mixture of organic molecules of the two sexes contains similar and different particles; the similar ones are those which have been extracted from every part common to both sexes. The different particles are those which have been extracted from the parts whereby the sexes are distinguished; thus there is, in this mixture, double the number of organic molecules to form the head, or the heart, or such other parts common to both, whereas there are only what are requisite to form the parts of the sex. Now the similar particles may act upon each other without being disordered, and collect together as if they had been extracted from the same body; but the dissimilar parts cannot act on each other, nor unite together, because they have not any relation; hence these particles will preserve their nature without mixture, and will fix of themselves the first, without the need of being penetrated by the others. Thus the molecules proceeding from the sexual parts will be the first fixed, and all the rest which are common to both, will afterwards fix indiscriminately, whether they are those of the male or female, and form an organized being which, in its sexual parts, will perfectly resemble its father, if it is a male, and its mother if a female; but which may resemble one another, or both, in all the other parts of the body. It seems to me that if this was well understood, we shall in a great measure be enabled to answer the objections made to the sentiments pf Aristotle, and which might also be advanced against this system. The question is, Why each individual, male and female, does not produce of itself an animal of its own sex? It must be acknowledged this question seems to carry weight with it; but having reflected a long time on this subject I think I have found an answer, and which I shall endeavour to explain.