URINE. 201 



For further information on this subject I must refer to the 

 excellent little work by Dr. Golding Bird on ' Urinary Deposits/ 

 from which the above observations are chiefly taken.] 



1 1 . Carbonate of lime. 



[Carbonate of lime is a rare ingredient of urinary deposits. 

 Dr. Griffith 1 describes it as consisting " of nuclei which were 

 almost colourless, and studded with minute acicular crystals all 

 over their surfaces." 



It is occasionally met with in the alkaline urine common in 

 cases of paraplegia following injury to the spine. In the majority 

 of cases it forms an amorphous deposit mixed with prisms of 

 ammoniaco-magnesian phosphate. More rarely it is met with 

 regularly crystallized, in compound spherical crystals, apparently 

 built up of an infinite number of close-packed needles, radiating 

 from a common centre. The outline of these masses is irregular, 

 and their periphery is often apparently serrated. (Fig. 30* c.) 

 The carbonate of lime is normally present in the urine of many 

 of the grammivora, especially of the horse. The dense deposit 

 which forms in the urine of this animal consists of a mixture of 

 carbonate and oxalate of lime. The former series form large 

 spherical crystals like glass beads, which, when immersed in 

 balsam, present the radiated acicular structure above described. 

 (Fig. 30* a b.) Very beautiful evidence of structure is exhibited 

 in these crystals of carbonate of lime when examined by polarized 

 light; a series of coloured rings traversed by a black cross being 

 visible.] 



12. Cystin. 



[Cystin, when present in the urine, forms a nearly white or 

 pale fawn-coloured pulverulent deposit, resembling the pale 

 variety of urate of ammonia. 2 It appears to be merely diffused 

 through the urine whilst in the bladder, as at the moment of 

 emission the secretion is always turbid, and very soon deposits 

 a copious sediment. On applying heat to the urine, the deposit 

 undergoes no change, which serves to distinguish it from urate 



1 Med. Gaz., March 1844. 



2 It is, however, always crystallized, a few regular six-sided laminae being often 

 seen, but the great mass consisting of numerous superposed plates, so that the com- 

 pound crystals thus produced appear multangular, as if sharply crenate at the margin, 

 (fig. 32 b.} They thus resemble little white rosettes, when viewed by reflected light. 



