=Inflammation= of this structure, (_myelitis_,) presents the same character, and may be followed by the same results as inflammation of the brain. From the distension and engorgement of the capillaries of the inflamed part, a bright red color may be presented, not only on the surface, but in the substance of the cord when exposed by division. Blood may also be found effused in the substance of the cord, or between its membranes, or between the bony walls and the dura mater. =Softening= of the spinal cord, may arise either spontaneously, or as a consequence of injury. When spontaneously taking place, a large portion of the cord may be involved. The appearance presented, is most usually that of a soft pulpy mass, which easily breaks down upon the opening of the membranes. When the result of injury, the softening is generally confined to the portion involved in the original violence. =Hardening= of the spinal marrow, (_sclerosis_,) may be one of the results of inflammation, yet the accompanying symptoms may vary so slightly from those of other forms of spinal disease, that the post-mortem alone, will disclose the true nature of the difficulty. In _locomotor ataxy_, the posterior columns of the cord are usually affected with this change. =Atrophy= of the spinal cord, differs from hardening, in the _shrinking_ which attends the progress of the disease, although there may be increased density, as in the former case. The essential peculiarity of atrophy, consists in an increased development of the fibrous elements of the cord, which by pressure, gradually destroys the elementary nerve constituents. This disease is confined chiefly to men of a middle age, and is generally the result of venereal excesses; muscular over-exertion, exposure to cold, &c., may also be exciting causes. =Morbid Growths=, of various kinds, and closely resembling those found in the brain, as well as _animal parasites_, are sometimes found in the spinal cord. PART II. THE NECK AND CHEST. CHAPTER I. OPERATION ON THE NECK.