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Consider, likewise, the vast proportion of seeds and pollen, of ova and young, a thousand or more to one, which come to nothing, and are therefore purposeless in the same sense, and only in the same sense, as are Darwin's unimproved and unused slight variations. The world is full of such cases; and these must answer the argument, for we cannot, except by thus showing that it proves too much.
As already stated, such passage of the ova from the ovaries into the womb occurs every twenty-eight days, and it is accomplished by a more or less copious flow of blood, a sort of hemorrhage, which carries the ova down through the fallopian tubes, and deposits them in the womb.
By his studies of parasitic castration Geoffrey Smith was led to formulate a theory for the explanation of somatic sex-characters different from that of hormones. He found that in the normal female crab the blood contained fatty substances which were absorbed by the ovaries for the production of the yolk of the ova.
There was above EACH of the lateral tufts of bristles a branchia, simple on a few of the foremost segments, and then strongly arborescent to the end of the body. The animal, a female filled with ova, evidently, from these characters, belongs to the family of the Amphinomidae; the only family the members of which, being excellent swimmers, live in the open sea.
In the bats and lemurs the "horns" are very short, and the lower common part is longer. Finally, in the apes and in man the blending of the two halves is complete, and there is only the one simple, pear-shaped uterine pouch, into which the oviducts open on each side. This simple uterus is a late evolutionary product, and is found ONLY in the ape and man. Origin of human ova in the female ovary.
To begin with, nobody has ever so much as distinguished between male and female eels; except microscopically, eels have never been seen in the act of spawning, nor observed anywhere with mature eggs. The ova themselves are wholly unknown: the mode of their production is a dead secret.
Since less than 500 ova are required to insure regularity in the menstrual function, it is clear that, if the surgeon finds it necessary to remove one of the ovaries, the other will provide abundantly for menstruation and for the bearing of children.
For a short time after they are impregnated they are fairly hardy, but from then till shortly before they hatch out the very slightest concussion will kill or seriously injure them. The management of sea-trout ova is similar to that of salmon, and the ova are obtained in the same way.
From the inside of each ovary the tiny eggs, or ova, grow, just as the ovules grow in the plant ovary or seed-pod. At first they are a part of the ovary; later they grow larger and fall loose, until the ovary is filled with them. The ovary is always inside the fish. It is there when the fish is born, and even then there are the tiniest hints of ova in it.
I have no doubt that an infinitely greater proportion of trout ova are eaten by the trout themselves than by grayling in rivers which contain both fish. Chalk streams and those rivers with gravelly bottoms and with alternate shallows and pools seem to be the most suited to the grayling. Among coarse fish the rudd is one of the best from the fly-fisher's point of view.
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