" Birds which have once copulated almost all continue to lay prolific eggs," but simply " almost all continue to lay eggs ;" the word " prolific" is an addition by Fabricius. But it is one thing to have birds conceiving eggs after intercourse, and another to say that these eggs are fruitful through this intercourse. And this is the more obvious from Aristotle's previous words, where he says, " Nor in the family of birds can those eggs even that are produced by intercourse acquire their full size unless the intercourse between the sexes be continued. And the reason is, that as the menstrual excretion in women is attracted by the intercourse of their husbands, (for the uterus, being warmed, draws the moisture, and the passages are opened,) so in birds it comes to pass that, as the menstruous discharge takes place very gradually, because of its being in small quantity, it cannot make its way externally, but is contained superiorly as high as the waist, and only distils down into the uterus itself. For the egg is increased by this, just as the foetus of oviparous animals is nourished by that which reaches it through the umbilicus. For when once birds have copulated, almost all continue to lay eggs, but of small size and imperfect " and therefore unprolific, for the perfection of an egg is its being fertile. If, therefore, without continued intercourse, not even those eggs that were conceived in consequence of intercourse grow to their proper size, or, as Fabricius interprets it, are " perfected," much less are those eggs prolific which fowls continue to lay independently of intercourse with the male bird.
But lest any one should think that these words, "for the uterus warmed, draws, and the passages are opened," signify that the uterus can attract the semen masculinum into its cavity, let them be aware that the philosopher does not say that the uterus attracts the semen from without into its cavity, but that in females, from the veins and passages, opened by the heat of intercourse, the menstruous blood is attracted from its own body ; so in birds the blood is attracted to the uterus, warmed by repeated intercourse, whereby the eggs grow, as the foetus of oviparous animals grows through the umbilicus.
But what Fabricius adds upon that cavity or bursa, in which he thinks the semen of the cock may be stored up for a w r hole year, has been already refuted by us, where we have stated that it contains no seminal fluid, and that it exists in the cock as
