The bladder in the fetus is long and conical, and is situated altogether above the upper border of the ossa pubis, which are as yet small and undeveloped. It is, indeed, an abdominal viscus, and is connected superiorly with a fibrous cord, called the urachus, of which it appears to be an expansion.
The urachus is continued upward to the umbilicus, and becomes connected with the umbilical cord. In animals it is a pervious duct, and is continuous with one of the membranes of the embryo, the allantois. It has been found pervious in the human fetus, and the urine has been passed through the umbilicus. Calculous concretions have also been found in its course.
The uterus, in the early periods of embryonic existence, appears bifid, from the large size of the Fallopian tubes, and the small development of the body of the organ. At the end of the fourth month, the body assumes a larger bulk, and the bifid appearance is lost. The cervix uteri in the fetus is larger than the body of the organ.
LETTER XXIV.
PHENOMENA OF LABOR.
Meaning of the Term—Its Divisions—Duration—Is Pain a Natural Condition of Labor?—Ether and Chloroform.
Having, in the preceding letters, spoken of the various conditions of pregnancy, I propose now making some remarks on the subject of labor.
I use the term labor in the medical sense, which means the same thing as delivery, or that process of nature by which the fetus, the secundinus or membranes, and the placenta or after-birth, are brought into the world.
In order to give you clearer ideas respecting labors, it is proper that I should say something in regard to the different kinds that may occur. On this subject authors have varied somewhat; some having divided labors into few classes, while others have designated many. But first, a few remarks on the cause of labor.
I have remarked in another place, that among women the natural term of utero-gestation is forty weeks, or nine calendar months. Occasionally, it is true, the expulsory process commences within this period, or in other cases extends beyond it; but on the whole, it happens so nearly at this period, that we are compelled to conclude that it must be under the influence of some particular agency, the nature of which we can in no wise comprehend.
Some have maintained that it is the weight of the child, forcing it downward at this precise period, which causes it to be expelled. Others have supposed that the uterus contracts at the end of the forty weeks, merely because it has no power of further expansion.