Attitude of the Fœtus.
The arms, it will be seen, are crossed on the breast, upon which the chin is also bent; the thighs are close together, and brought against the Abdomen; the legs are close bent on the Thighs, and the feet are turned up against the front of the legs, the whole body being curved forward.
The position in which the Fœtus most usually lies in the Womb has already been shown, particularly in Plate XII, and in Plate XVI. The head is downwards, and the back part of it turned to the mother's left side. What is the cause of this almost universal position is not certainly known. It was formerly thought to depend on the head being heavier than the other parts, and thus sinking down; but this supposition has been shown to be entirely without foundation. M. P. Dubois has lately advanced the notion that it depends on an instinctive feeling in the Fœtus itself, which directs it to take that position by which it can most easily make its exit. This opinion appears very reasonable, and is apparently well founded. It is well known that the Fœtus is susceptible of various impressions while in the Womb, and impelled by unerring instinct to take the breast immediately it is born; nay, it has even been known to suck the finger of the assistant, in cases of face presentation, even before birth! We can readily believe, therefore, that it is directed to place itself in the Womb, in the best position, the same as it is directed to take the finger in its mouth.
In the young of many of the lower animals this is also strikingly exemplified. The young duck in the shell taps with its little beak against the part that is to be broken, and rushes into the water even with a part of the shell still on its back. The young oppossums, who are born imperfect from the Womb, shelter themselves, immediately they come into the world, in the pouch on the mother's breast, and fasten themselves to the mammæ till they are more perfectly grown.
It must be remarked however, that the head does not always present first, though it usually does so. Occasionally we have the breech present, and still rarer even other parts; but these are merely exceptional deviations, the causes of which are unknown. Out of every sixteen children born, fifteen usually come head first. This however, will be shown better further on.