Approaches to the analysis of theory choice in science studies often focus either on objective criteria or subjective values for evaluating theories or on critical experiments for testing theories. In the present article a historical case study in the biomedical sciences is reconstructed, in which experimentation was performed to choose between two competing theories of blood coagulation. Analysis of this case study reveals that experimentation exhibits a particular structure, composed of design, execution, and results, and specific characteristics, consisting of controllability, (...) reproducibility, plasticity, and fecundity. Although this structure and these characteristics are not used to replace objective criteria or subjective values of theory evaluation or to define critical experiments, they are instrumental for analyzing and understanding theory choice. (shrink)