The concept of the organism in physiology

Summary The growth of physiology in the 19^th and 20^th centuries was accompanied by the development of disciplinary boundaries between physiology and other biological sciences. Physiology became the study of the mechanisms that underlie the functions of organisms and their component parts. Concern with the internal workings of organisms has led physiologists to focus on the maintenance of homeostasis in the internal environment rather than on the interactions of organisms with their external environments. Moreover, interest in the cellular or biochemical mechanisms that underlie organismal function has resulted in the use of inbred populations of laboratory animals in which these mechanisms can be most rigorously studied. Finally, emphasis on the function of fully developed or adult organisms has been accompanied by a relative neglect of developmental processes. Disregard for the environment, for variation, and for development has made possible major advances in our knowledge of physiological mechanisms but has led to an impoverished concept of organisms. Incorporation of evolutionary, ecological, and developmental perspectives into the study of organisms might help to unite physiology more closely with the other biological sciences and lead to a richer and fuller understanding of organisms.