 Based on such a view, the dependence of the reference of theoretical terms in science on a description or on its relation to a currently accepted theory can be avoided. This is what made causal theories of reference attractive to philosophers of biology, who saw continuity in the use of the term “gene” despite significant theoretical shifts in genetics during the twentieth century. This view suggests the following narrative regarding the events presented in Part 1: Mendel had identified a natural kind when he identified gametic elements involved in the inheritance of characters. Early Mendelians used a variety of terms but referred to the same entity when performing hybridization experiments. Later the units were named “genes” but the communicative chain connecting earlier and later uses of the terms referring to entities belonging to the natural kind remained intact. And even if the meaning of the concept changed, i.e., various properties shared by the members of the kind were suggested or dropped from the list of necessary and sufficient criteria, eventually, a molecular characterization of genes was achieved, which explained the most stable observed properties (or their variation under varying conditions) and was since available for expert geneticists to determine whether something was a gene or not. Much of the debate sketched in the following can be described as discussing to what extent this narrative is adequate.