Pathology (Greek, pathos, "disease"), the science which deals with life under abnormal conditions. This science was for the most part limited in former days to the study of symptoms and treatment, but within the last century there have been considerable additions to the knowledge of the anatomy of disease, the naked-eye appearances and the tissue changes revealed by the microscope having been studied carefully. The subject of pathological chemistry has also grown up, and the study of physiology, which deals with animal functions in health, has greatly modified the notions concerning diseased processes. The germ theory, moreover, has led to many new developments in pathology. The science deals with such subject matter as Atrophy, Hypertrophy, the various forms of Degeneration (q.v.), Tumour-formation [Tumours], Inflammation (q.v.), and the relation of parasites to disease.