EXCESS OF UREA. 715 



excess, and has in these instances been ascribed to a process 

 of rapid or excessive oxidation intimately related to heat-pro- 

 duction and the pyrexial state. It is, however, highly probable 

 that the elevation of body-temperature, so prominent a feature 

 in fevers, may be accounted for in other ways than as the result 

 of activity of the oxidizing process ; while it seems certain 

 that in horses, at least, excess of urea in the urine does occur 

 in conditions rather the opposite of hyperoxidation. In those 

 animals we meet with this condition when after liberal dieting, 

 particularly with albuminous substances and a full amount of 

 work or exercise, there follows a period of enforced idleness. 



These cases are not, as in man, of gradual development, but 

 rather of sudden occurrence, unattended with premonitory 

 symptoms, and the condition of excess of urea in the secretion 

 is associated with marked alteration of its colour. 



The rapid and remarkable changes which occur in the 

 exchanges amongst the various tissues and elements, and the 

 chemistry of these disturbed activities, is ill-understood and 

 requires investigation. The peculiar and extreme nervous 

 disturbance, uroemic poisoning — or urtemia as this condition of 

 the retention or entrance into the blood of excrementitious 

 material is sometimes called — and which so often attends or 

 follows upon certain cases marked by excess of urea in the 

 urine, at one time believed to be due to the conversion of the 

 retained urea into carbonate of ammonia, is probably dependent 

 upon other conditions altogether. It is more likely to follow 

 not the retention in the blood of one material, but many, the 

 result of the breaking up of nitrogenous compounds which, in 

 the processes of the natural exchanges, ought to have been 

 eliminated by the kidneys. 



It is apparently the result of a disturbance of many changes 

 which are ever occurring in the blood, the proper execution 

 of which is essential to normal nutrition, particularly of nerve- 

 tissue. That there are numerous and different changes always 

 occurring we know from their action and results, but how 

 produced we do not as yet understand. 



d. Excess of Colouring Matter. — The varying shades of 

 colour which occur in urine in disease are probably due to 

 more than one matter ; nor are these always the same, nor 

 present in similar proportions. Although not in possession of 



