In his recent article, Nicolas Rasmussen (2001) is harshly critical of what he terms 'empirical philosophy of science', a philosophy that takes seriously the history of science in advancing philosophical pronouncements about science. He motivates his criticism by reflecting on recent history in microbiology involving the 'discovery' of a new bacterial organelle, the mesosome, during the 1950's and 1960's, and the subsequent retraction of this discovery by experimental microbiologists during the late 1970's and early 1980's. In particular, he argues that there was a lack of constancy in the methods microbiologists used in approaching the issue of the existence of mesosomes, and that in fact a similar sort of 'methodological flux' pervades all experimental work. My goal here is to refute Rasmussen's doctrine of flux, and in turn to re-establish order in our understanding of the methods and strategies of experimenters. My strategy in achieving this goal is to re-visit the same crucial research articles in the history of the mesosome episode that Rasmussen (2001) visits; and what I find upon returning to this literature is not flux, as Rasmussen seems to find, but a constancy of method in experimental reasoning, a constancy codified by what I call 'reliable process reasoning'.