18 MODE OF PRODUCTION 



pended being increased, but it would appear esta- 

 blished that there is a decided falling off in the gross 

 amount of solids discharged from the system, and 

 this may be explained in the following manner. 

 Urea is found in the blood : it would seem to be the 

 product of a species of decomposition of animal 

 matter going on during the circulation of that fluid, 

 the quantity of it excreted from the system being 

 greatest after the consumption of azotised food, and 

 commensurate with the proportion of animal prin- 

 ciples existing in the blood. Now, during the pro- 

 gress of chronic nephritis it has been shown that the 

 blood becomes impoverished, the albumen escaping 

 from it in the urine being replaced by water, and the 

 debility being still further increased from the impe- 

 diment to nutrition occasioned by the frequent com- 

 plication of vomiting and diarrhoea. 



The substitution of water for the important prin- 

 ciple, albumen, must necessarily diminish the quantity 

 of those azotised matters formed in the blood by 

 the decomposition or deterioration of its more ani- 

 malised portion, and hence the deficiency of urea and 

 the lithates in this disease. Viewed in this light, 

 the low specific gravity of the urine cannot be con- 

 sidered as indicating more than an impoverished 

 condition of the blood, which state we know may 

 also occur in many other diseases, and hence any 

 value which might otherwise attach to this symptom 

 as diagnostic of this particular affection must be 

 rendered doubtful till future experiments shall decide 

 as to whether a similar state of the urine does not 

 accompany the same condition of the blood in every 



