 If jumbles are considered undesirable from an ontological point of view, it is also possible to construe experimental systems as purely conceptual entities. They are ways of acting in a laboratory, and action is always guided by concepts. Material things, insofar as they appear in experimental practice, are only parts of an experimental system to the extent in which they are subject to purposeful experimental action. They can only be subject to such action to the extent to which they are recognized by an experimenter, for example, as a microsomal fraction or an antiserum with a certain antigen specificity, and so on. A biological sample without its label and some researcher who knows what this label means is of no value whatsoever; in fact, it isn’t even a biological sample.