Contested inheritance: debates on the role of 'inheritance of acquired characteristics' in late nineteenth century Darwinian and Weismannian thought

Debates over transgenerational inheritance of acquired characters under the banner of epigenetics research, while contested, are becoming increasingly mainstream. However, given the polysemic nature of the terms 'epigenetics' 'transgenerational' and 'inheritance of acquired characters', facets of this debate, both historically and contemporarily, actually relate to and are indeed reinforced by the terms undifferentiated usage. In order to shed light on the terminological constraints at play today, this historical analysis focuses on a parallel debate which unfolded on the pages of Nature in 1893 and 1894 relating to the meaning of 'acquired characters' between four very different protagonists: Sir Edward Fry, Ray Lankester, Edward Poulton and Joseph Cunningham. As differing groups of researchers both historical and today use undifferentiated terminology to represent differing phenomena I argue that as the terms' meaning is ambiguous, a more careful analysis of the concepts and mechanisms they have been used to represent should be undertaken; particularly in relation to theories concerning 'external conditions' or the role of the environment in evolutionary processes. There is also a need to develop a clearer understanding of the role of polysemantic or undifferentiated terminology in scientific disputes, debates, transdisciplinary communication, group identity formation in the sciences and achieving consensus.