Abstract: A method of X-ray crystallography for investigating microscopic crystals, in particular microscopic crystals of biological macromolecules, comprises the steps of extruding a sample stream (1) with an injector nozzle device (100), wherein the sample stream (1) comprises a viscous liquid with microscopic crystals embedded therein, providing an X-ray beam (2) with a synchrotron source device (210) and irradiating the sample stream (1) with the X-ray beam (2), and collecting diffraction image data created by diffraction of the X-ray beam (2) by the microscopic crystals with a series of X-ray exposures of the sample stream (1). Furthermore, an injector nozzle device (100) and an X-ray crystallography apparatus (200) for X-ray crystallography investigations of microscopic crystals are described.