6 ANTENATAL PATHOLOGY AND HYGIENE
natal pathological life from one another are small when contrasted with the characters which serve to distinguish neonatal from post- natal morbid changes, and very small indeed when put alongside the deep-seated diversity of antenatal pathology. The differences found in the diseases of the new-born have given origin to a separate nomen- clature for them, a neonatal nosology ; and we speak of icterus neonatorum, syphilis neonatorum, and meltena neonatorum as if they were superficially different, at any rate, from the jaundice and the syphilis and the mehena of the adult. But such dissimilarity exists between the pathological phenomena which occur before birth, and those which are met with after it, as to suggest essential differences in nature and causation. This is specially true of teratological phenomena. They are startlingly unlike anything else in the whole range of pathology. It is to this peculiarity more than to any other that Teratology owes the isolated position that it has so long occupied. Like Corea among the nations has Teratology been among the sciences : a hermit kingdom, a hermit science ! To the onlooker it has seemed as if neither had any part to play outside its own narrow limits. Yet is the whilom hermit subject capable of profoundly influencing the other departments of medical research and of being influenced by them. As the subject opens out we shall see in detail what these age-incidence differences in pathology consist in ; meanwhile, it may be repeated that from this standpoint there is a pathology of post- natal life, of intranatal life, and of antenatal life.
The Divisions of Antenatal Life.
On first thoughts, the nine months of intrauterine life and the twelve hours of intranatal transition seem small and of little import in comparison with the threescore and ten years to which it is expected that postnatal life may be prolonged. It is doubtful, how- ever, if any twelve hours after birth are just so full of possibilities, physiological and pathological, as is the time during which the foetus is passing through the maternal canals ; and it is certain that no period of nine months in childhood, in adult life, or in old age is so replete with occurrences, so diverse in kind, and of such far-reaching importance as is that spent by the unborn infant in utero. There is an intensity and a variety in the processes of antenatal life which have no equal at any other time. Therefore, notwithstanding the shortness of intrauterine existence, it has become necessary to subdivide it into at least three periods, and between these there is the same deep-seated diversity as that which marks off antenatal life from the rest of life. Further, it is no exaggeration to say that few medical men have a very clear conception of the progress of events during antenatal life. The drama of embryonic and foetal develop- ment and growth is, so to speak, going on, but the curtain has not been rung up, and the spectators get only confused impressions from the swaying of the drop-scene and from vague sounds, excursions and alarms, coming from behind it ; yet no one doubts the existence of great activity iiost cortinam theatri, and some from superior know-
