The passage quoted by St. Alphonsus as that of the Septuagint is not exact even as the Septuagint has it. The full text is: "If two men fight, and one strike a woman that hath [29] in a fine he shall be mulcted; whatsoever the husband layeth upon him he shall give according to decision [i.e., of the judges]. But if it [the babe] be fully formed he will give life for life, eye for eye, tooth for tooth, hand for hand, foot for foot, burning for burning, wound for wound, stripe for stripe."
This is (1) evidently nothing but an application of the Lex Talionis, with no thought whatever of the biological animation, as such, of the fetus. It means that if a fully formed fetus be aborted, either no real damage is done, as such a child is viable; or the formed child may be maimed, and then the Lex Talionis is to be applied. If the fetus is not fully formed it is not a fit subject of the Lex Talionis since it cannot lose an eye, a tooth, and so on, because it lacks these organs and therefore the law of retaliation is not to be enforced.
(2) Suppose, however, the writer of the text as the Septuagint has it did think with St. Alphonsus that the formed fetus is animated, and the unformed is not animated, even then the conclusion drawn by St. Alphonsus is not warranted by the text. The laws of Exodus do not teach embryology, physiology, or any other part of physical science; and no authority worth a hearing holds that the Scriptures were intended to be infallible treatises on obstetrics or astronomy. Like the other parts of the Bible, the laws of Exodus presuppose the unscientific biological, astronomical, and other physical notions of the time in which they were written—the moral truth is the matter the Scripture is dealing with; there no inaccuracy is to be found. St. John (1:13) speaks of those who believe in Christ's name, "Qui non ex sanguinibus, neque ex voluntate carnis, neque ex voluntate viri, sed ex Deo nati sunt." Here he expresses the contemporary notion, which is also the Thomistic opinion, that men are generated from the specialized blood of their parents. He was interested solely in conveying the truth that those who received Christ were regenerated by him, not through heredity; and he does so, although the biology is inexact. If St. Alphonsus's conclusion is valid as from the text of Exodus, then men are generated ex sanguinibus, and so on indefinitely.
The Massoretic text of this passage seems to be the best preserved: "If men fight, and one hurt a woman who is with child, and her child come forth, yet there is no mischief, he [who struck her] shall be mulcted in a fine; whatsoever the husband of the woman layeth upon him he shall pay according to the judges. But if there be mischief, then he shall give life for life, eye for eye, tooth for tooth, hand for hand, foot for foot, burning for burning, wound for wound, stripe for stripe." Here the Hebrew text follows the Lex Talionis exactly. If, in a brawl, a man's pregnant wife is struck and abortion results, the offender pays the penalty. If the abortion does not kill or maim the child, the culprit is fined by the Sanhedrim; if the child is killed or maimed, then the penalty is according to the Lex Talionis. In the Hebrew text also there is no mention of a distinction between a foetus formatus and non formatus.
Whether the fetus is animated at conception or some time later, there is no foundation whatever for the notion that the female is quickened later than the male. As was said before, Aristotle held that the human male fetus is animated at the fortieth day, the female at the ninetieth day, and the old moralists accepted his statement. At the fortieth day, however, no one can differentiate sex unless the microscope is used, and this particular use of the microscope is altogether modern—the knowledge requisite for such use was not in existence sixty years ago. At the twentieth day, with the microscope and a stained specimen, a biologist can recognize whether the primordial ova are present or absent and thus determine sex. Only at the eighty-fourth day can sex now be differentiated without the aid of the microscope, but then the embryo must be dissected: nothing can be told from its external appearance. Sex can first be distinguished by the external appearance only at about the one hundred and twelfth day, the end of the fourth month of gestation. Therefore when Aristotle said the male fetus is animated at the fortieth day, and the female at the eightieth or ninetieth day, he was romancing.
The question, then, narrows to this: Is any human fetus animated immediately at conception, or from forty to eighty days after conception? The reason given by the followers of Aristotle for deferring animation is that the vital principle requires organs in the receptive material, but the embryo in the early stages, they say, lacks these organs. This notion, however, as to the lack of organs is altogether erroneous, and the rational soul enters the embryo in the oval stage, immediately after the pronuclei unite: there is organization in that stage of human life sufficient to receive the substantial form or soul. We do not know how long after insemination the pronuclei unite, but the proposition here is that as soon as they unite the human soul enters. Fecundation usually occurs after a menstruation, but not necessarily so; the spermatozoön may live in the tube for seventeen days awaiting the ovum.
The human body is made up of billions of microscopic living cells, all of which are derived by fission and differentiation from the two original single germ-cells, the ovum and the spermatozoön. Some nerve-cells have long processes running along the white fibres through the entire length of the body, but they cannot be differentiated except by the microscope. In the body are also various liquids which are not cellular, as water, saliva, tears, urine, blood and lymph plasma, and the gastric, intestinal, and glandular juices, and these are secreted or excreted by the somatic cells. The cells assimilate nutritive material carried to them by the blood, excrete refuse substances, secrete glandular products, and are the media for all human operations below certain acts of the intellect.
A typical animal cell is commonly spherical in shape, but it may take a great variety of forms through compression. It has a cell-body or protoplasm, which is called also cytoplasm, especially when contrasted with the nuclear karyoplasm, and a nucleus. A few cells, like fat-cells and the human ovum, have an external covering membrane, or cell-wall. There is a part called the Centrosome observable in many cells, and this is made up of one or two minute dots surrounded by a radiating aster called the Attraction-Sphere. The centrosome is concerned in the process of cell-division and in the fertilization of the ovum; it is an important organ in the production of cell from cell, though its full nature and function are not yet known. The Plastid, or Protoplast, is another less important part found in certain cells; and in this by enlargement and differentiation are formed starch, pigment, and in some cases chlorophyl. Vacuoles are seen in cells; and there is an opinion that these may be a special kind of plastid: some vacuoles pulsate.
The Nucleus is the most important part of a cell, the centre of its activity. The specific qualities of organism in origin and development are based upon nuclei, so far as the material element of the living cells is concerned. Vital stimuli pass through the nucleus into the surrounding protoplasm, and these stimuli control metabolism. The nutritive cytoplasm assimilates, but the vital principle energizes this assimilation through the nucleus, for a part of a cell deprived of the nucleus may live for a time, but it cannot repair itself. Constructive metabolism ceases when the nucleus is lost. A toxic disease like diphtheria kills by disintegrating cellular nuclei.
In the nucleus are several elements, the chief among which is Chromatin. Chromatin takes various forms, but commonly it is an irregular network. From the chromatin are derived the Chromosomes in the prophases of indirect cell-division which is the process of cell-division in the human body, except in lymph-cells and white blood-corpuscles, which split directly, or by Amitosis. Indirect cell-division is called Mitosis or Karyokinesis. In the male and female chromosomes, according to a common opinion of biologists, all the elements of parental and phyletic physical heredity are transmitted to the embryo.