This paper discusses some philosophical and historical connections between, and within, nineteenth century evolutionism and microscopical research. The principal actors are mainly Darwin, Schleiden, Whewell and the "London Doctors," Arthur Henfrey and Edwin Lankester. I demonstrate that the apparent alliances—particularly Darwin/Schleiden (through evolutionism) and Schleiden/Whewell (through Kantian philosophy of science)—obscure the deep methodological differences between evolutionist and microscopical biology that lingered on until the mid-twentieth century. Through an understanding of the little known significance of Schleiden's programme of microscopical research and (...) by comparing certain features of his methodology to the activities of the "London Doctors," we can identify the origin of this state of affairs. In addition, the outcome provides an insight into a critique of Buchdahl's view on Schleiden's philosophical conception. (shrink)