 While some account of the phenomenon under study is generally adopted before researchers set out to identify the responsible mechanism, the characterization often changes radically as research on the responsible mechanism proceeds (Bechtel &amp; Richardson 1993 [2010], refer to researchers reconstituting the phenomenon). This is illustrated with an example from the study of cells. A starting point for early inquiries into how animals store energy for their activities focused on the heat generated by metabolizing foodstuffs. This heat was assumed to power other activities and approximately a hundred years of research was devoted to explaining animal heat (see Mendelsohn 1964). However, after Lohmann (1929) and Fiske and Subbarow (1929) had identified adenosine triphosphate (ATP) and demonstrated that when hydrolyzed it would release considerable energy, heat was determined to be just a waste product of metabolism and researchers instead focused on the synthesis and hydrolysis of ATP. This became the reconstituted phenomenon to which much of the older research was now applied.