 Moreover, there is no need to identify the material basis of the genotypic constituents shared by the inbred line. Nevertheless, Mendel’s experiments had begun to expose the constituents’ nature. When inbred lines were crossed then self-pollinated, the traits of individuals raised under uniform conditions could be analyzed statistically by employing—and thereby demonstrating—a model of genotypic constituents as pairs of segregating factors. In these experiments, phenotypes and genotypes as classes still play a role, with the F2 phenotypes being used to identify whether apparently identical F1 phenotypes are heterozygote or homozygote genotypes. It might be asked whether Johannsen’s reference to the “finer methods of measuring or description” could be construed to include the disambiguating analysis of ratios after inbreeding, crossing, and self-pollination? If the answer is yes, the inbred parent could be classified as a different phenotype from the F1 hybrid. In that case, the Johannsenian study of heredity would amount to generating phenotypes—classes of organisms distinguished by “finer methods of measuring or description” of traits—that are isomorphic with genotypes—classes of organisms that share identical stable constituents. 