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The journey is fraught with momentous consequences, for it is during this passage through the oviduct that the fate of the ovum is determined. If it is to develop into a living creature, a great many conditions must sooner or later be fulfilled; but there is one which must be promptly satisfied.
In all the Gnathostomes the Wolffian duct is converted into the spermaduct, and the Mullerian duct into the oviduct. Only one of them is retained in each sex; the other either disappears altogether, or only leaves relics in the shape of rudimentary organs.
We thus learn that the laying is effected by periodical emissions, broken with intervals of rest. As long as she does not feel ripe eggs coming to her oviduct, the greenbottle remains in the sun, hovering to and fro and sipping modest mouthfuls from the carcass.
While it is not certainly known, it is probable that the ovum is capable of impregnation any time during its sojourn within the oviduct and before reaching the uterus, or probably for a period of about one week from the time of its escape from the Graafian follicle.
However far withdrawn into the centre of the pea, the Bruchus, whether larvae or nymph, is reached by the long oviduct. It receives an egg in its tender flesh, and the thing is done. Without possibility of defence, since it is by now a somnolent grub or a helpless pupa, the embryo weevil is eaten until nothing but skin remains.
And it is practically certain that these cells meet in the oviduct, even in that portion of it which receives the ovum just as it leaves the ovary. Thither a number of the male cells have traveled by their own activity; several come in contact with the ovum and one, but only one, actually enters it.
When the ovum has ripened, it becomes detached from the ovary, and enters a fleshy tube about the size of a lead pencil, known as the oviduct. There are two of these tubes, one running from the neighborhood of each ovary; both enter the uterus, but on opposite sides. The ovum travels down the tube which corresponds to the ovary where it originated.
These are closely set upon the inner surface of the oviduct; their outer ends are free and continually sway to and fro like a wheat field on a windy day; and by their motion they create a current in the direction in which the ovum should move, namely, toward the uterus. While passing through the oviduct, the ovum has no attachment whatever to the mother, yet development is going on all the time.
The second one we opened and found one egg broken near the vent and another with shell formed ready to be laid. Rupture of the oviduct was probably the cause of the hens dying on the nest and is due to the same condition in the hens; that is, the straining to expel the egg necessary in the engorged condition of the internal organs from overfatness. Melons for Fowls.
The remarkable vitality of the spermatozoa even under less favorable circumstances direct observation shows that these elements retain their movements for over nine days outside of the body renders it almost certain that their powers of fertilization are maintained for a long time after they are deposited within the healthy female genital tract; it is believed that the spermatozoa are capable of fertilization after a sojourn of three or more weeks within the oviduct.
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