412 URINE. 



modifications in fever, and perhaps more especially in the quantita- 

 tive increase and the qualitative alterations of the urinary pigment. 

 Soberer has, moreover, endeavoured to show that these processes 

 of fermentation, in so far as they occur within the bladder, con- 

 tribute largely towards the formation of calculi. Thus, for instance, 

 it depends solely upon the character of the vesical mucous and upon 

 the nature of the fermentative process induced by it, whether the 

 urinary concretion that is formed consist of uric acid, earthy phos- 

 phates, or urate of ammonia. The varying conditions of decom- 

 position at different periods of the disease, that is to say, the 

 gradual qualitative and quantitative change of the secretion of the 

 morbidly affected mucous membrane, may afford an explanation of 

 the formation of urinary calculi whose various layers have a 

 different composition. Scherer thus seeks for one of the most im- 

 portant causes of lithiasis in a degeneration of the secretion of 

 the vesical mucous membrane a mode of explanation which de- 

 rives support from the chemical investigations of urinary con- 

 cretions as well as from medical experience. The majority of these 

 urinary concretions contain a clot of mucus as a nucleus, whence it 

 would appear that the mucus generally affords the first formative 

 basis for the concretions ; then, moreover, the inner layers of most 

 calculi contain uric acid, whilst the outer ones contain earthy phos- 

 phates or urate of ammonia ; a trace of uric acid, if nothing more, 

 may always be detected in the nucleus of the concretion. Every 

 uric acid concretion aids, by irritating the vesical mucous mem- 

 brane, in increasing its own size by the deposition of phosphates or 

 of the urates of ammonia and of lime ; whilst it is obvious, from the 

 formation of calculi, that at the commencement of their deposition 

 mucus must almost always be present, and there must, at the same 

 time, be a tendency to the separation of uric acid, in short, an 

 acid urinary fermentation. The uppermost layers of most urinary 

 calculi show that, at the time of their deposition, an alkaline ferment 

 was present, and that its action had already been established in the 

 urine. All who have examined the constitution and formation of nu- 

 merous urinary concretions, more especially of the larger ones, must 

 be led almost involuntarily to the adoption of Scherer's view. Even 

 the mulberry calculi, which undoubtedly contain a very large pro- 

 portion of oxalate of lime, but probably never consist solely of 

 this substance, furnish additional corroboration in support of this 

 mode of explanation, for they always contain a large quantity of 

 uric acid, and frequently constitute the nucleus of larger earthy 

 concretions. 



