is surrounded by warm olive oil, which, however, is not in immediate contact with its surface, but is separated from it by a delicate flexible membrane of a kind which has already been referred to by the author in several of his published papers, and which prevents any escape of the oil by the side of the blood-vessels and other structures entering the hilus of the gland.… When the instrument is in use, the kidney lies between two delicate, exceedingly flexible membranes, which apply themselves closely to its surface and to the surface of the structures entering the hilus of the organ, and each of these membranes forms with each of the symmetrical halves of the box a chamber which is filled with oil and which communicates by a relatively wide flexible tube with the recording instrument.” Experiment “4. After the immediate effect of the operation has passed off, the volume of the kidney will usually remain unchanged (with exception of the changes due to the pulse and respiration) for many hours unless some change in the conditions of the experiment be intentionally introduced. “5. When the _Traube-Hering_ curves of the blood-pressure present themselves, the volume of the kidney does not expand with the rhythmic rise in the blood-pressure. With each rise of the blood-pressure the kidney _contracts_, expanding with each fall of the blood-pressure. The renal vessels are, therefore, amongst those to the rhythmic contraction and expansion of which the _Traube-Hering_ waves are due. “6. Arrest for 3 or 4 minutes of the artificial respiration, where that is employed, and where curare has been previously injected, causes a contraction of the renal vessels (which may reach 12 per cent of the post-mortem volume of the kidney) simultaneously with the rise of aortic blood pressure which is produced by the asphyxia. “7. Stimulation of the medulla oblongata by weak induced currents causes a powerful contraction of the renal vessels. “8. Stimulation of the central end of a sensory nerve, _e.g._, sciatic, brachial plexus, splanchnic, &c., causes a contraction of the renal vessels simultaneous with the rise in the aortic blood-pressure. Stimulation of the central end of the vagus causes a contraction of the kidney (where the vagus of the other side has been cut to eliminate reflex inhibition of the heart), and the renal vessels _contract_ whether the stimulation of the central end of the vagus cause a rise or a fall of the aortic blood-pressure. “9. Stimulation of nearly all the roots of the splanchnic in the thorax, and of both larger and smaller splanchnic nerve-trunks causes contraction of the kidney of the _opposite_ side. The extent to which the kidney contracts on stimulation of the splanchnic is usually very considerable. In one case the kidney contracted on stimulating with a strong induced current for three minutes to an extent which was equal to 63 per cent. of the post-mortem volume of the organ.