The experimental study of the urine as a toxic factor consists in the administration to animals of the urine and the several substances which compose it. If injected subcutaneously we find that it acts as a poison, and if given in sufficient quantity will cause death. In the latter case a fairly constant chain of symptoms is observed. The first is an extreme degree of diuresis, - so great is the amount of urine passed and so frequent the urinations that Bouchard claims that the urine is the most powerful of all diuretics. Contraction of the pupil is almost invariably noticed, the animal becomes feeble, the respirations shorter and quicker, somnolence follows which may be interrupted by convulsions, the body temperature falls and death with muscular tremors follows, the heart being arrested in diastole. In this train of symptoms we are compelled to see the resemblance to the clinical picture of uremia, either from chronic renal disease or from ligature of the ureters. When the kidneys of rabbits are removed there are at first no noticeable effects, the animals moving freely and eating as usual. A state of great irritability then supervenes and slight stimuli evoke great uneasiness. Convulsions of groups of muscles increasing to general tonic and clonic spasms then occur which soon give place to a condition of stuporous anesthesia, followed in some eighty hours by death.

Normal urine is toxic when injected subcutaneously in amounts varying from 30 cc. to 60 cc. per K. weight; the urines of disease are toxic in greater or less amounts according to the variation in its components. The ability of the urinary poisons to produce structural changes has been shown by recent studies in which it is found that ulceration of the stomach and small intestine is an occasional result of nephritis and uremia. Some twenty-two cases have been collected (2) and the lesions seem to be due to toxic materials circulating in the blood rather than to infarction of the vessels supplying the ulcerated area.