Ludwig wrote a classic monograph on renal secretion. He theorized that urine formation could be explained purely in terms of the laws of physics and chemistry, and that under the hydrostatic pressure of the blood in the capillaries of the glomerulus, protein and cell-free fluid is separated from the blood by a simple physical process of filtration. This theory contradicted Bowman’s contention that the glomerulus secretes fluid. See also Ludwig’s habitation thesis, from which the above work was expanded: De viribus physicis secretionem urinae adjuvantibus. Marburg, Elwert, 1842. Digital facsimile of th 1843 work from Goethe Univerität at this link.

Ludwig changed Poiseuille’s hemodynamometer into the kymograph by the addition of a float and caused this float to write on a recording cylinder. Abridged English translation in Ruskin (No. 3160.1).

In this development of his theory of urinary secretion (see No. 1232) Ludwig made important observations on endosmosis.

The innervation of the salivary glands first elucidated.

Ludwig’s inaugural address at Leipzig, in which he introduced the idea of keeping alive excised portions of organs by means of artificial circulation, or perfusion. He suggested that the blood-pressure had a stimulating effect on the vagus.

Discovery of the vasomotor reflexes.