This text proposes a critical analysis of some recent pieces of work in the sоciology
of sсiences using the language of "actors-networks" and "heterogeneous engineering".
It scrutinizes the way these notions are presented Justified and used in the description
of empirical studies. Following this critical study, the text proposes a sociological
model of the practice of science which is meant to be reflexive, in harmony with
the present state of knowledge about the microdynamics of research, and which takes
into account the structural constraints of the practice of science. The model attempts
to identify, from among the infinite variations brought to light in the many micro-histories
of scientific practices, those constants that unite them.