406 MANUAL OF PHYSIOLOGY. 



raerated, although their accurate study belongs rather to pathol- 

 ogy. First among these to be named is 



Albumin, which occurs from (1) any great increase in the blood 

 pressure in the renal vessels, whether caused by increased inflow 

 or impeded outflow. (2) Excess of albumin in the blood, and, 

 strange to say, some forms of albumin escape much more readily 

 than others. Thus, egg albumin, globulin or peptone, if intro- 

 duced artificially into the blood, is soon found in the urine. 

 (3) A watery condition of the blood, such as would give rise 

 to oedema elsewhere. (4) Total abstinence from NaCl for some 

 time. (5) Extensive destruction of the epithelium of the urinary 

 tubes. 



Next in importance to albumin are the following : 



Grape sugar; of which normally only the merest trace occurs 

 in the urine, although there is always a certain quantity in the 

 blood. It is present in large quantities in (1) the disease known 

 as diabetes, when a great quantity of pale urine with a very high 

 specific gravity is passed. (2) After injury of a certain part of 

 the floor of the fourth ventricle of the brain. -(3) After poisoning 

 by curara, carbonic oxide and nitrate of amyl. In short, any 

 disturbance of the circulation of the liver gives rise to an increase 

 of sugar in the blood, and when the amount reaches 6 per cent, 

 it appears in the urine. 



Bile Acids and Pigments appear in the urine when, from occlu- 

 sion of the bile ducts, they find their way into the blood. 



Leucin and Tyrosin also occur in the urine, but only after pro- 

 found interference with the function of the liver. 



The urine undergoes important changes after being voided, the 

 explanation of which is of much interest to the practitioner, and 

 must be understood by the student of medicine. (1) Com- 

 monly enough the urine loses its transparency as soon as it gets 

 cold, though perfectly clear when passed, or when again heated 

 to the body temperature, for the urates are soluble in warm but 

 almost insoluble in cold water. This " muddiness," which soon 

 settles down, as a more or less brightly colored sediment, is 

 chiefly caused by the precipitation of acid sodium urate, stained 

 with a coloring matter derived from the urochrome. When 



