30 DISEASES OF THE KIDNEY. 



normal when the outlook is favorable. According to prevalent 

 modern views, the cause of the uraemic symptoms is due to insuf- 

 ficient elimination by the kidneys of certain products of the body 

 which, when sufficiently concentrated in the tissues, have a poison- 

 ous action upon them, especially upon certain parts of the brain. 

 This poisonous effect is exercised chiefly by the urea and its prod- 

 uct of decomposition, carbonate of ammonia. 



According to Jtosenstein, however, poisoning by carbonate of 

 ammonia alone induces but one of the trains of symptoms, that of 

 epilepsy, while the agent which produces the uraemia occasions not 

 only epilepsy, but coma, convulsions, and delirium. Moreover, we 

 must remember that in cases of uraemia, even when the presence of 

 carbonate of ammonia in the blood has been demonstrated, the de- 

 pendence of the ursemic symptoms upon its presence has not been 

 proved. The quantity of urea excreted in the course of a day is 

 generally diminished in Bright's disease. This diminution of the 

 daily quantum of excretion is often considerable at the very time 

 when the secretion of urine is also reduced ; while in patients with 

 extreme polyuria, whose health is as yet unshaken, the quantity of 

 urea excreted, in spite of the small percentage contained in the 

 urine, may even exceed the normal. If the daily excretion of urea 

 is very small, we are justified in fearing that the disproportion be- 

 tween production and excretion may lead to uraemia.] 



In many cases of Bright's disease, the patients observe a grad- 

 ual failure of their power of vision ; in others, blindness, more or 

 less complete, sets in suddenly. I have heard a patient, upon com- 

 ing to himself, after a uraemic convulsion followed by coma, ask to 

 have the gas lit, although it was burning brightly at the time. This 

 partial or total extinction of vision, too, used formerly to be re- 

 ferred to uraemic intoxication, and was called uraemic amblyopia or 

 amaurosis. Latterly, however, the real source of this disorder has 

 been found to be an extravasation into the retina, accompanied by 

 inflammation. A diagnosis of Bright's disease has repeatedly been 

 made by means of the ophthalmoscope alone. In one case which I 

 have watched, the impairment and subsequent improvement of vis- 

 ion which occurred manifestly coincided with the formation and 

 absorption of such extravasations. 



[This disturbance of vision is not to be confounded with another 

 urwmic amaurosis which appears sometimes superadded to an 

 already existing retinitis, and sometimes comes on suddenly with 

 the other uraemic signs, without previous derangement of the sight. 

 In a few days, or even in a few hours, the sight fails so that a light 

 cannot be distinguished ; but should the uraemia subside, vision may 



