The anatomy and physiology of the nerves have been so successfully investigated of laie years, that an opportunity is afforded of explaining many of the complicated phenomena of disease, by a consideration of the functions of this intricate system. I propose in this essay to endeavor to account for certain symptoms observed under circumstances of privation of nervous influence, of which I am not awarö that any satisfactory explanation has yet been offered. It is now generally admitted, that after injuries of the spine, death is frequently occasioned by disease in the urinary bladder, accompanied by an ammoniacal condition of the urine. The same has been observed in paraplegia arising from other causes, as ramollissement of the medulla spinalis,* or tumors in the spinal canal. Mr. H. Cline invariably found, aller paraplegia had been produced by the injuries he inflicted on the spinal marrow of dogs, that the bladder became affected.The object, then, of my inquiry, is to ascertain whether the disorganization of the bladder, and alkaline condition of the urine, after injuries and diseases of the spinal cord causing paralysis, are dependent upon the loss of nervous influence.The explanation which has been given by many surgeons is,f that "in consequence of the bladder having lost its nervous energy, the urine becomes decomposed in that organ, as it does after it is voided under ordinary circumstances, and thus acts as an irritant on the mucous coat." This exposition, I think, admits of question, since we have no evidence whatever that mucous membranes exert any influence over the fluids which are in contact with them, otherwise loan through the medium of their secretions, or by absorption ; nor is there any apparent necessity for the bladder possessing tbe property of preventing decomposition of the urine. The different parts of the animal machine, although often beautifully accommodating themselves to altered conditions, are still intended for existence in a healthy, not in a diseased state : hence, when the functions of the bladder are unimpaired, if ils contents should remain sufficiently long to become decomposed, there is a stimulus to evacuation, and the mine is expelled. That the urine may, and frequently does, become decomposed from long continuance in the bladder, is sufficiently obvious ; for when It is relieved in cases of retention of urine, or enlargement of the prostate gland, a strong ammoniacal odor is often emitted.