He distinguishes three forms—(1) _the inflammatory_, (2) _the waxy_, (3) _the cirrhotic or contracting_; the first originating in the tubules, the second in the vessels, and the third in the connective tissue of the organ. 1. _The Inflammatory Form._ This has three stages: that of inflammation, that of fatty transformation, and that of atrophy. The disease may prove fatal at any stage of its course. In the first stage, an exudation is poured out, and a destruction of the epithelium takes place. This exudation, affecting a large number of tubules, leads to enlargement of the organ, and also to fatty degeneration of the epithelium; its absorption or removal, leads to ultimate atrophy. There is also a _fatty degeneration_, to which we will refer later, which is unattended either with albuminuria or with dropsy, and which does not, therefore, belong to this category. In this stage of inflammation, the organ is of the natural size, or slightly enlarged; its capsule is unaltered, and can be peeled off readily; its surface is smooth, more or less congested, often pink, sometimes of a dark purplish color, sometimes mottled, pale and purple. On section, the cortical substance is found relatively enlarged, and often congested. The Malpighian bodies stand out prominently from the surrounding tissues, the congested vessels, separated by a varying amount of white (somewhat opaque) deposit, composed of the altered tubules. The vascular spaces between the cones and the cortical substance are uniformly distended with blood. The cones are usually redder than the cortical substances, and from the engorgement of their vessels and the altered condition of their tubules, they present a series of alternating red and white lines, converging to the apex of the cone, at which point the white distinctly predominates. The pelvis of the kidney is natural. Examination with the higher powers of the microscope shows the Malpighian bodies dense and granular. The tubules are more bulky than natural, and their epithelium is swollen, granular and dense, while within them is frequently seen a transparent homogeneous exuded material, binding into one mass, the epithelium of the tubules. Blood corpuscles are frequently found incorporated in this exuded material. In the stage of fatty transformation, the organ is enlarged; its capsule natural; its surface smooth or slightly lobulated. It is pale and fatty in color, and on its surface stellate vessels are frequently seen. On section, the cortical substance is pale, of a yellowish-white color, and increased in volume, while the cones are pink, and of natural color and size. The Malpighian bodies do not project prominently as in the first stage.