 Johannsen placed not only the developmental processes, but also the material make-up of the germ cells or the genes outside the scope of his genotype-conception of heredity: “[T]he nature of the ‘genes’… is as yet of no value to propose any hypothesis” (1911: 133). Yet, the shift (mentioned earlier), where the focus in studies of heredity moved on to the material make-up, was prefigured by his referring to the genotypical constitution and noting that “a ‘genotype’ is the sum total of all the ‘genes’ in a gamete or in a zygote” (1911: 132–3). A further shift towards exposing the dynamics of development that build on those constituents was prefigured when Johannsen referred to “phenotypes… i.e., the reactions of the genotypical constituents” (1911: 145). 