As a rule there is no allantoic placenta forming the means of communication between the blood of the parent and the foetus, and when such a structure does occur its development is incomplete.
A distinction must be drawn between the above and diseases, like syphilis and small-pox, in which the contagion of, not the tendency to, the disease is transmitted directly to the foetus in utero.
U, Umbilical vein of the foetus, rlf, The right lateral fissure.
Malformations of the pelvis, accidental injuries and the diseases and displacements to which the uterus is liable, on the one hand; and, on the other, various morbid conditions of the ovum or placenta leading to the death of the foetus, are among the direct local causes.
No distinction is now made as to whether the foetus is or is not alive, legislation appearing to make the offence statutory with the object of prohibiting any risk to the life of the mother.
Indeed, the tendency in continental Europe is to regard the abortion as a crime against the unborn child, and several codes (notably that of the German Empire) expressly recognize the life of the foetus, while others make the penalty more severe if abortion has been caused in the later stages of pregnancy, or if the woman is married.
It was also a very common practice to destroy the foetus, but parents were affectionate towards their children.
Near affinity; and while more nearly related to the Marsupialia (q.v.), in which an imperfect allantoic placenta is sometimes developed, it is broadly distinguished therefrom by the invariable presence of a functional placenta by the aid of which the foetus is nourished throughout the greater portion of intra-uterine life.