Based on an empirical analytical study conducted in a biology laboratory, the article investigates the construction of scientific knowledge in the process of toxoplasma DNA extraction. It accompanies all stages in the construction of this knowledge, from selection of humans through their transformation into numbers. Latour's concept of circulating reference, along with the concepts Hacking employs to explain the construction of the objects of science and of ideas, marks, and things, are vital to understanding this shift from human to number. The present study hopes to stimulate a more critical attitude towards the construction of the objects of science. It also stresses that it would be problematic to use numbers or marks as our sole references in health interventions.
circulating reference; ideas-marks-things; construction; health care