Description:
<jats:p>The biological sciences have become increasingly reliant on so-called ‘model organisms’. I argue that in this domain, the concept of a <jats:italic>descriptive model</jats:italic> is essential for understanding scientific practice. Using a case study, I show how such a model was formulated in a preexplanatory context for subsequent use as a prototype from which explanations ultimately may be generated both within the immediate domain of the original model and in additional, related domains. To develop this concept of a descriptive model, I focus on use of the nematode worm <jats:italic>Caenorhabditis elegans</jats:italic> and the wiring diagrams that were developed as models of its neural structure. In addition, implications of the concept of a descriptive model, particularly its relevance for the data-phenomena distinction as well as its relation to long-standing debates on realism, are briefly examined.</jats:p>