[Footnote AH: The word _ginnus_ is used by Aristotle in two senses: the first to denote in general an imperfect animal, an abortion, a dwarf animal, proceeding sometimes from the horse and the ass; and the second to signify the particular produce of the mule and the mare.] These experiments, however simple, have never yet been tried with a view to explain the nature of generation. I regret that it has not been in my power to try them, as I am persuaded consequences would result from them, which at present we only conjecture, and speak of as presumptions. I imagine, for example, that of all the above copulations, that of the great mule with the female bardeau, (the animal produced by the horse and ass) and that of the male-bardeau and she-mule might possibly not succeed: that the junction of the he and she-mule, and that of the male and female-bardeau, might sometimes be attended with success, though not often. That the he-mule would produce with the mare with greater certainty than with the she-ass, and the male-bardeau with more certainty with the she-ass than with the mare; and that the horse and he-ass might possibly produce with both the she-mules, but that the ass would be more successful than the horse. These experiments should be made in a country at least as warm as the south of France; and the age of the mules should be seven, the horses five, and the asses four years, because those different periods are necessary before those three animals acquire their full vigour.