 By the beginning of the twentieth century few biologists investigating cells (Driesch, 1914, being a notable exception) espoused vital forces and vitalism per se ceased to be regarded as a tenable position. But many biologists were still concerned to account for differences between living cells and ordinary material systems. A prominent position adopted by many investigators (Haldane 1929, 1931; Lillie 1934; Needham 1936; Russell 1945, 1930; Von Bertalanffy 1952; Weiss 1963; Woodger 1929) was holism, sometimes referred to as organicism. (See Nicholson and Gawne 2015, for a discussion of how the organicists differentiated their position from both vitalism and mechanism.) Holists accepted that living systems were built out of material parts. They insisted, however, that the activities performed by components of living systems depended not just on those components and their composition but on their organization. Accordingly, one cannot just add together the activities of the components to account for the whole (“the whole is not just the sum of its parts”). The organized whole in part determines how the parts behave. This attitude is manifest, for example, in J. S. Haldane’s opposition to investigating the origins of life from non-living matter: “There is and can be no origin of life out of mechanical conditions. Such an origin is inconceivable” (Haldane 1930: 12).