A controversy between the well-known medical teacher Herman Boerhaave and the anatomist Frederik Ruysch on the nature of the glands shows how chemical knowledge had a decisive influence on the way in which Boerhaave perceived the anatomy and working of the glands. While Ruysch maintained that the glands are no more than the extremities of arteries and act as mechanical instruments separating the fluids into smaller particles, Boerhaave examined the glands as membranous follicles in which chemical processes prepare the fluids for their different uses in the body. Boerhaave, in other words, turned to the chemical properties of particles rather than the vessels that contain them. Boerhaave's viewpoint was new and resulted from his belief in chemistry as the discipline par excellence for the explanation of the most basic processes in the body. More than anything else, the controversy shows how chemistry was not contained within fixed disciplinary boundaries, but had a decisive influence on Boerhaave's construction of anatomical knowledge.