Experimental Systems:

Entry Encyclopedia for the History of the Life Sciences In the autobiographical report on his laboratory work at the Pasteur Institute in Paris, the French molecular biologist François Jacob remarked a decade and a half ago: " In biology, any study … begins with the choice of a 'system.' Everything depends on this choice: the range within which the experimenter can move, the character of the questions he is able to ask, and often also the answers he can give " (Jacob 1987, p. 261). In the biological research literature, the notion of " experimental system " for the characterization of experimental arrangements has been in regular use since the first decades of the twentieth century, in particular in connection with the establishment of a vigorous in vitro biology (see, e.g., Gale and Folkes 1954, p. 1224) and with the coming into use of a variety of model organisms, especially bacteria and viruses, two features of experimental systems to which I will come back later. When Jacob speaks about " system, " the term is used in exactly this sense. A comparison may help set the stage. Two centuries ago, toward the end of the eighteenth century, when natural historians and biologists talked about " systems, " they meant systems of thought such as the " system of the eggs " or the " system of the sperms " with respect to the then concurring theories of generation, into which, sporadically, experimental arguments were inserted. Two hundred years later, it is experimental systems that determine the research context into which theorems can eventually become inserted.