 For inbred lines, in contrast to the realm of natural varying populations, the phenotype-as-class is not used to identify the genotype-as-class; indeed it is recognized as a phenotype because the genotype, which is the inbred line, is given. As far as Johannsen’s experiments could discern, the genotype-as-material-constituents could be the whole germ cell or seed. Reintegration would entail conceptualizing the action of these constituents of the genotype-as-whole-cell and finding methods to investigate their influence on the development over time of the organism’s traits (see entry on  developmental biology).  Such a program had proponents, especially in the first half of the twentieth century, but came to be eclipsed by Mendelian genetics and discounted by historians and philosophers of heredity (Sapp 1987).