208 EXCRETION. 



estimates that 4*5 grains consist of creatine, and 7 grains, of 

 creatinine. 1 



Oxalate of Lime, CaO,C 3 O 3 + 2HO. 



This salt is not constantly present in the normal human 

 urine, though it may exist in considerable quantity without 

 denoting any pathological condition. It is exceedingly inso- 

 luble, and the appearance of its crystals in urinary deposits is 

 very characteristic. According to Robin, a trace may be re- A 

 tained in solution by the chlorides and the alkaline phosphates 

 in the urine. 3 This salt may find its way out of the system 

 by the kidneys, after it has been taken with vegetable food 

 or with certain medicinal substances. The ordinary rhubarb, 

 or pie-plant, contains a large quantity of oxalate of lime, 

 which, when this article is taken, will pass into the urine. 

 It is probable, however, that a certain quantity of the oxa- 

 late may be formed in the organism. Pathologists now 

 recognize a condition called oxaluria, characterized by the 

 appearance of oxalate-of-lime crystals in the urinary sedi- 

 ments ; and sometimes the quantity in the urine is so large, 

 and its presence is so constant, that it forms vesical calculi 

 of considerable size. 



Inasmuch as pathological facts have shown pretty con- 

 clusively that oxalic acid may appear in the system without 

 being introduced with the food, some physiologists have en- 

 deavored to show how it may originate from a change in cer- 

 tain other of the proximate principles from which it can be 

 produced artificially out of the body. One of the substances 

 from which oxalic acid can be thus formed is uric acid. It 

 remains, however, to show that this may take place in the 

 living organism. Woehler and Frerichs injected into the 

 jugular vein of a dog a solution containing about twenty- 

 three grains of urate of ammonia. In the urine, taken a 



1 THUDICHUM, A Treatise on the Pathology of the Urine, London, 1858, p. 

 416. 



2 ROBIN, Lemons sur les humeurs, Paris, 1867, p. 674. 



