The child at term, as a rough average, is from 48 to 52 centimetres (19 to 201⁄2 inches) in length, and it weighs from about 63⁄5 to 71⁄2 pounds. It is impossible, however, to obtain the sizes and weights of infants in utero with scientific accuracy, because the date of conception cannot be determined with absolute certainty, and individual fetuses vary as do infants after birth. A full-term infant sometimes may weigh only 31⁄2 pounds when the mother is diseased, and again an eight-month fetus will weigh as much as 8 pounds. Large muscular and fat women have large babies; women of the well-to-do classes have larger babies than do the poor; women who work during gestation bear smaller babies than do those women that rest. Mothers who work in tobacco, lead, or phosphorus have puny babies; white children are larger at birth than negro children; boys at term are 3 to 5 ounces heavier than girls.
Langstein says that prematurely born infants weighing from 900 grammes (311⁄2 ounces) to 1500 grammes (31⁄2 pounds)—that is, all born before the seventh solar month—must be kept in hot-water incubators in a room with ordinary ventilation. Babies weighing 2000 grammes (41⁄2 pounds) or more get along in an ordinary crib if they are kept surrounded with hot-water bags. Such children are to be fed with human milk through a catheter passed into the mouth or they die of inanition. Only a few of them are strong enough to suck from a bottle, and these give up the effort after a few days and die. They cannot utilize fat, even from milk; and all artificial food is dangerous.
Most of the prematurely born become rachitic, and even human milk is not preventive of this condition. Rachitis is a constitutional disease, characterized by impaired nutrition of the bones and changes in their shape. In the third or fourth month craniotabes is frequent—that is, an atrophy of the skull bones with the formation of small conical pits. These infants show also a morbid tendency to convulsions—spasmophilia. Such diseases are caused by a lack of mineral salts, which normally are carried to the fetus by the placental blood during the last two months of gestation. Because of this lack premature infants require the administration of lime salts in their food; they also need iron because they are anemic.
A fetus, then, of six calendar, or solar, months (not lunar) is viable if treated in a hospital by competent physicians. Otherwise it is not viable, except in a strictly technical sense; it will not live more than a few days or weeks. Reports of infants younger than six months as having been successfully reared are not credible—it is easy to make an error in the reckoning.
A full seven-months infant may be reared with proper feeding and skilled care; a six-months infant may be reared (with difficulty) in a hospital with skilled care. If it is certain that the removal of a six-months fetus will here and now save the life of a mother (a very difficult matter to judge by the best diagnosticians), this removal may be done, provided the infant is delivered in circumstances where skilled care, incubator, and proper food are obtainable; otherwise the removal is not justifiable. That the ordinary physician says it is necessary to empty the uterus is not a sufficient reason, as he is likely to act from ill-digested information set forth by professorial pagans, who place no value whatever on human life in an infant.
A most important and essential circumstance in the matter of inducing abortion at the end of the sixth month of gestation to save a mother's life is that in practically every case requiring such interference the diseased condition of the mother has checked the growth of the fetus, and the fetus therefore is really not a six-months child in development. Such an undeveloped fetus is not viable. Eclamptic women, and those who have nephritis, are most likely to have undeveloped fetuses. In cases of this kind the seventh month should be completed before interference.
How is this human body in all its complexity developed from the microscopic germ-cells? There has been a vast deal of ink spilled in striving to solve this mystery, but we come out empty by the same door wherein we went. The early Preformationists guessed that the ovum contains an embryo fully formed in miniature, and development is a mere unfolding of what had already existed. The biologists of to-day mention the Preformationists with superior scorn, and then present Preformationism under other names. Weismann's theory is the most fashionable at present.
In a paper read at the Darwinian Memorial Congress in 1909, Weismann said: "With others I regard the minimal amount of substance which is contained within the nucleus of the germ-cells in the form of rods, bands, or granules, as the germ-substance, or germ-plasm, and I call the individual granules[37] ids. There is always a multiplicity of such ids present in the nucleus, either occurring individually or united in the forms of rods and bands (chromosomes). Each id contains the primary constituents of the whole individual, so that several ids are concerned in the development of a new individual." Actually there are such things as chromosomes, and when these are stained and are under the highest power of the microscope they appear to be granular. These granules Weismann calls ids. Beyond the fact that there are such granules, all else is sheer guessing.
He says further: "In every complex structure thousands of primary constituents must go to make up a single id; these I call determinants, and I mean by this name very small individual particles, far beyond the limit of microscopic visibility, vital units, which feed, grow, and multiply by division. These determinants control the parts of the developing embryo,—in what manner need not here concern us."
There is some truth here. The id is made up of molecules and atoms, ions and electrons, and in some manner, of course, these have to do with the development of the embryo; but as to the manner we have not the slightest knowledge, and just this knowledge is what we need to make the theory anything more dignified than a child's game at guessing. There is a structural differentiation in the unsegmented ovum, with all the embryonal axes foreshadowed in it, but this tells us nothing more than that the egg contains the man in germ.