The escape or expulsion of the Germinal Vesicle from the Ovum, or Egg, leaves, as we have already explained, a passage to its very centre, thus enabling the Zoospermes, or male animalculæ, to enter. If both are perfect and healthy, impregnation is then complete. The first change that now takes place is observed in the Vitellus, or yellow of the Egg, which at once forms itself into a mass of little globules; and it is a singular fact that these are always a fixed even number, generally beginning with four or six, and so multiplying or doubling—always, however, keeping the number even. If by chance they should end their self-arrangement by an odd number, a perfect being could not be formed—the impregnation would end either in an abortion or an unnatural growth in the Womb. It generally takes two or three days for the globules to arrange themselves, and meantime the Zoosperme, or male principle, remains dormant. The globules soon begin to form themselves either into Testicles or Ovaries, as the sex may be, of the future being. At the same time myriads of smaller globules break off from them and spread all round the Zoosperme, which is soon entirely covered or coated with them. They now grow together and form the skin. The Zoosperme is supposed to be the head and spine, and the globules, which thus form the skin, shut out our view from observing any further formations. The Testicles, or Ovaries, as the case may be, are now quite prominent, though we cannot yet determine the sex, even with the most powerful microscope, nor is there any form to the new being other than the original shape of the male animalculæ.