AGE-INCIDENCE OF MORBID PROCESSES 5
Hoffmann (66). Since then the study of the diseases of the foetus, as distinct from the monstrosities, has made great advances, until now there has been accumulated a large library of books l^earing on this subdidsion of Antenatal Pathology. Still more near the surface of the ocean of literature (to return for a moment to our comparison) lie the works in which the morbid predispositions to diseases and deformity, and the mysterious phenomena of heredity, are considered ; in them is to be found much that is of value, along with much that is at the best hypothetical.
This, then, is the literature of Antenatal Pathology, or rather it is the literature upon which it is hoped that the subject of Antenatal Pathology may yet be built up ; for few, if any, attempts have been made to bring together the monstrosities, and the foetal diseases, and the morbid predispositions, and treat them as subdivisions of one separate and self-contained department of medicine. It is in this that the novelty of Antenatal Pathology consists ; the subject is surveyed from a new point of view, with a vastly widened horizon.
The Age-Incidence of Morbid Processes.
It is conceivable that morbid influences may act upon the individual during three epochs in his existence : they may act after, during, or before birth. In other words, their influence may be exerted in postnatal, in intranatal, or in antenatal life. The results of their action vary with the period during which they act, and hence it comes that there is a postnatal, an intranatal, and an antenatal subdivision of pathology. It goes without remark that it is about postnatal pathology that most is known, for from birth up to death morbid causes are seen at work, and their effects are patent to all. Injuries, poisons, microbes, and parasites all play a part in producing the numerous and varied changes in the structure and functions of the body so fully described in medical and surgical text-books. When pathology is spoken of, it is usually postnatal pathology that is meant.
Even in postnatal pathology the age-incidence of morbid processes can be recognised as an important subdividing factor ; differences there are between the pathological changes which are characteristic of advanced age and those which occur in adult life, or in childhood, or in infancy. The rheumatism of childhood, for instance, is very different in its clinical manifestations from that of adult life. In the former, erythema marginatum and papulatum, painless subcutaneous nodules situated over the bony prominences of the knee, elbow, ankle, and spine, and endocarditis and chorea are marked symptoms ; while acute pain and tenderness in the joints, high fever, and profuse sweating are often entirely absent. In the rheumatism of adult life, on the other hand, erythemata, nodules, and chorea are uncommon, while grave arthritic developments are frequent. Heart disease also differs in its characters according as it is met with in the child or adult ; and there is the typical senile heart.
The differences, however, which mark off these epochs of post-
