 Furthermore, Weber moves from general characterizations of concepts to an empirical study of reference to particular genes in Drosophila in the context of investigative practices in genetics, such as the molecular cloning of genes in the context of developmental biology (see  §1.4).  Even though reference and description of classical and various versions of molecular gene concepts differ, it turns out that the classical concept is utilized in identifying genes (e.g., those involved in the organization of the fly embryo), which are then made subject to molecular characterization (Weber 2005: Ch 7; see also Waters 1994). Thus, despite a lack of complete co-extension of the classical and the molecular gene concepts, partial referential continuity plays a significant role in mediating investigative practices.