These parasites appear to produce either by a direct action or by the occlusion of vessels, ulceration, and hemorrhages from the urinary mucous membrane, including that of the bladder. These effects are supposed to be due to the blocking of the smaller vessels by the worms themselves. An adherent deposit consisting of masses of distoma eggs and grains of uric acid sometimes forms in grayish-yellow patches within the ureter, and gives rise to stricture, with dilatation and hydro-nephrosis above. This parasite has been considered the cause of the endemic hæmaturia of hot countries, but as cases of this affection have been carefully examined {67} for the distoma with negative results, it must be considered as only one among several causes. Strongyli are said to have been found in some of the cases. Nothing is known of an appropriate TREATMENT for the distoma. An abundant flow of urine might perhaps carry off more rapidly such individuals as have found their way into the urinary passages, and, considering the character of the deposit described above as causing stoppage of the ureter, treatment directed against the uric-acid diathesis might diminish the risk of this particular form of trouble. Diseases of the Ureters. Absence of the ureter may take place when one kidney is congenitally absent, though this is not an absolute rule, since the ureter may terminate above in a rounded sac. When a single kidney exists, consisting of the fusion of two, there are usually two ureters opening in the usual position. In one instance, in which only one kidney and one ureter were present, the ureter opened into the bladder on the side opposite to that upon which the kidney was situated. Not very infrequently two ureters exist in connection with a normal kidney, remaining separate for the whole or a part of their course to the bladder. This condition is merely a sort of exaggeration of the separation between the two branches of the renal pelvis. A few instances have been noted where a ureter or a fistula connected therewith has opened outside of the bladder at a point near the urethra. This malformation gave rise to symptoms of incontinence of urine, and in one case was remedied by operation. Abnormal openings of the ureter into the uterus and vagina as the results of pelvic inflammations, and upon the external surface as the result of wounds, have occurred. They are more or less amenable to surgical treatment, and belong to the domain of surgery and gynecology rather than to medicine.