188 THE SECRETIONS : 



and of biliphsein. The presence or absence of the constituents 

 of the blood may, however, be easily determined by the micro- 

 scope, and by certain tests. If undissolved blood-corpuscles 

 remain in the urine, as is frequently the case, they sink to the 

 bottom and form a dark brown-red sediment, in which their 

 forms may be recognized by the microscope. The dark-red 

 supernatant fluid coagulates on the application of heat, in the 

 same manner as ordinary albuminous urine; the coagulated 

 matter, however, in this case is not white, but of a dirty brown 

 colour. Similar appearances are produced by the addition of 

 nitric acid. If the blood-corpuscles are perfectly dissolved in 

 the urine, as I have sometimes observed to be the case, the 

 microscope affords us no assistance. The application of heat, 

 and the addition of nitric acid will, however, be sufficient to 

 convince us directly of the presence of albumen and haemato- 

 globulin. 



The quantitative determination of blood in urine, and the 

 changes which must be made, in consequence of the presence 

 of a considerable quantity of that fluid, in the determination 

 of the normal constituents are precisely similar to those already 

 described in speaking of albuminous urine. It must be ob- 

 served that the ash becomes reddened by the peroxide of iron 

 which occurs in the hsematin; and the fixed alkaline salts, as 

 well as the earthy phosphates, are increased by the fixed salts 

 of the blood, which usually amount to about 8 per cent. 



3. TJie constituents of the blood generally. 



Fibrin has been found associated with the other constituents 

 of the blood which we have described as occasionally occurring 

 in the urine. 1 Urine of this sort resembles blood in appear- 

 ance; assumes, on being allowed to rest, a gelatinous consis- 

 tence ; trembles on the movement of the vessel ; and, finally, 

 separates into two portions, a clot, and thin fluid serum. 



On examining, under the microscope, a little of the fluid 

 obtained by pressing a portion of the clot, blood-corpuscles are 



1 [Fibrin has been detected occurring in a state of solution in urine, independ- 

 ently of the other constituents of the blood. Zimmerman describes seven cases of 

 this nature, some of which are noticed at length in a future part of this chapter. 

 (Zur Analysis und Synthesis der pseudoplastischen Prozesse. Berlin, 1844, p. 129.)] 



