The changing image of the life sciences in the twentieth Century can be charted as the conscious attempt to introduce rigorous experimental, analytical and reductionist methods from the physical to the biological sciences. This change brought biology from being a largely descriptive to an experimental science that included both the laboratory and field. Of all the natural sciences, biology underwent the most profound sequence of changes during the twentieth Century. (Biology is defined here initially in the nineteenth-century sense, as the study of the structure and function-including aspects of general physiology — of living Systems, excluding medicine and medically-related subjects such as pharmacology, epidemiology and public health.) During the first half of the nineteenth Century biology was dominated largely by issues of natural history: taxonomy, new discoveries relating to geographic distribution, fossils and extinction, and of course comparative anatomy. Physiology was largely separate from Lamarck's general term of Biologie at the time, and was housed institutionally within medical schools and hospitals, as opposed to museums and botanical or zoological institutions. The connection of physiology to general biology was clearly recognized, but it shared a largely different intellectual and social base until at least the 1840s.