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in rosettes. The principal modifications which I have met with in 

 the size, form, and arrangement of these crystals, are well shown in 

 the eleven drawings which accompany this communication*. When 

 these crystals are kept in the dry state for a long time, they not 

 unfrequently break down and crumble into powder. 



The late Dr. Golding Bird, in his work on ' Urinary Deposits/ 

 has given a representation of some crystals which he has denominated 

 " penniform" describing them as consisting of a variety of the mag- 

 nesian phosphate ; the crystals figured do, however, undoubtedly 

 represent a modification of those of phosphate of lime. They are 

 represented in figure 4, taken from Dr. Bird's original specimen. 

 Although I have elsewhere pointed out this error, most recent writers 

 on the urine still persist in describing these crystals as a variety of 

 the phosphate of ammonia and magnesia. 



On the Frequency of their Occurrence. 



I find, as already stated, that phosphate of lime in the form of 

 crystals is of much more frequent occurrence in human urine than 

 the triple phosphate, excluding those cases of the presence of the 

 latter phosphate which are due to the decomposition of the urea of 

 the urine subsequent to its emission. I have met with deposits of 

 crystallized phosphate of lime in some hundreds of urines, and in 

 many different cases; it is therefore not a little remarkable, from 

 the frequency of its occurrence and the peculiarities presented by the 

 crystals, that it should have been so long overlooked. The micro- 

 scope therefore furnishes us in most cases with the ready means of 

 detecting the presence of deposits of phosphate of lime, as of so many 

 other urinary deposits. 



Characters of Urine depositing Crystallized Phosphate of Lime. 



The urine from which phosphate of lime is deposited is usually 

 pale, but occasionally it is high-coloured ; the quantity passed is large, 

 and the calls to void it frequent, more or less uneasiness and smart- 

 ing being occasioned by its passage, at the neck of the bladder and 

 along the course of the urethra : its specific gravity varies greatly ; 

 taking the whole quantity passed in twenty-four hours, it is usually 

 below the average, nevertheless the animal matter and urea are 



* The Figures on the preceding page represent selected portions of four of 

 these drawings : all the objects are magnified 100 diameters. 



