Although science communication scholars tend to focus primarily on the challenges faced when communicating science and scientific discoveries to the larger public, there is much to be learned from a closer look at the challenges faced by scientists when communicating among themselves. For example, scientists are frequently challenged by the need to adapt already existing language to new concepts and objects for which no descriptions yet exist (Keller, 2002). In that way, scientists must articulate a connection between words and the novel “things” found in experimental practice. In doing so, they must also endeavor to coordinate their rhetorical and material work with the larger social and economic components of the scientific enterprise. It is through these coordinating efforts that discoveries are able to move from the individual lab to the larger scientific arena. One of the most common scientific methods for extending previous forms of speech to new scientific discoveries is the use of model organisms. Briefly, models are animals, plants, or single-celled organisms meant to stand in for an entire class of organisms. Model organisms do three things. First, they provide a locus for experimental activity. Scientists can easily adapt model organisms for experimental purposes, and the model’s biological similarity to other creatures justifies scientists’ conclusion about entire classes of life. Second, these organisms provide a locus for the organization of disparate disciplines, scientists, tools, and socioeconomic resources. Third, these organisms provide the initial starting point for subsequent rhetorical presentation through argument from example (as described by Perelman & Olbrechts-Tyteca, 1969). That is, argument generated by research employing a specific model organism provides a shared conceptualization of entire arenas of biological investigation for those who accept the model’s use as valid. In the case of stem-cell research, which will be the focus of this chapter, two model organisms perform these varied functions. Those model organisms are the embryonic stem (ES) cells found in mice and the hematopoietic (blood-forming) stem cells (HSCs) found in adult humans. Each of these models embodies different qualities that define a “stem cell.” Use of the mouse model creates a stringent definition that discounts

the possibility of adult stem cells, while the hematopoietic model provides an expansive definition that justifies arguments stating all organs of the adult body have stem cells that are similar to ES cells. Of course, given their differences, tensions exist within and between these competing models. These tensions arise, in part, through interference and cooperation among three key components of science-the material, the social, and the rhetorical (Shapin & Schaffer, 1985). Among these three components, which will be detailed in the following section, tension is especially present between the social and rhetorical components. That is, while arguments generated through the use of model organisms can serve to justify universalizing conclusions and shared knowledge, the economic self-interest of science requires scientists to develop and protect resources devoted to their specific model organism. Through examples such as this, this chapter will argue that the use of model organisms in stem-cell research highlights the coordination of the material, social, and rhetorical components of science and, ultimately, illustrates how scientists engage in a continuous process of connecting words with things. Articulation theory further aids this endeavor by offering an explanation for how the three components of science relate and interact within this context. In exploring these relationships, this chapter will also recommend these components of science (as interpreted through articulation theory) as a framework for a robust rhetoric of science research program that justifies looking at all facets of science-from grant writing to hypothesis formation and experimental practice to science-public interactions.