PRODUCTS, ADVENTITIOUS. 



79 



species of calculus is remarkable for the'rough 

 tuberctilated character of its surface, which 

 gives it the aspect of a mulberry. Its section 

 exhibits commonly a granular, but sometimes 

 a laminated, arrangement ; the internal colour 

 is the same as the external ; the density and 

 hardness (especially of the laminated variety) 

 vary considerably. The dark colour of these 

 calculi is generally ascribed to admixture of the 

 colouring matter of blood, thrown out from the 

 irritation their rough surface produces on the 

 tissues it comes in contact with. The oxalate 

 of lime calculus may occur of pure white colour, 

 with sharp angular crystals on the surface ; of 

 this rare variety the University College Col- 

 lection contains a remarkable specimen. 



The rarity of oxalate of lime crystals in uri- 

 nary deposits was matter of received opinion 

 until the inquiries of Dr. G. Bird led him to 

 the inference that in the cases of disease oc- 

 curring in London ... the oxalate of lime is 

 of far more frequent occurrence in urine than 

 the deposits of earthy phosphates.* The oxa- 

 late deposit, when in abundance, appears to the 

 naked eye, after the application of gentle heat, 

 as a white glistening powder, which under a 

 low magnifying power resolves itself into " crys- 

 tals of the oxalate in beautifully formed trans- 

 parent octohedra,with sharply defined edges and 

 angles (Jig. 80, ). It sometimes happens that 



concerning oxalate of lime crystals. They (oc- 

 tohedral form) are of somewhat more frequent 

 occurrence in females (14 of 42) than in males 

 (11 of 42). They are most frequently present 

 in acute affections and in anaemia ; and at that 

 period of acute affections when anaemia is 

 most likely to be fully developed, at the onset 

 of convalescence. They occur in spermator- 

 rhea temporarily. Their frequency in rheuma- 

 tism has been exaggerated, our proportion being 

 only 3 of 15 cases. They are not present in 

 all cases of any given disease, and probably 

 originate in some special condition of the 

 blood. Observation continues to exhibit to 

 us the frequency of a deposit of oxalate of 

 lime crystals, at the period of convalescence 

 of acute diseases ; so much so that we regard 

 their sudden appearance in an acute disease as 

 a sign of that fortunate change. This deposit 

 is of temporary (say a few days) duration, 

 and not to be confounded with the more or 

 less permanent condition appertaining to a 

 peculiar diathesis. 



4. Of the cystin or cystic oxide calculus 

 there are two varieties, physically considered ; 

 and the physical peculiarities are probably re- 

 ferable to chemical differences. The pure 

 cystin calculus is of oval shape, acquires mo-, 

 derate size ; its surface, tolerably smooth, has 

 a crystallised aspect. Internally it appears 

 formed of a multitude of irregularly aggregated 

 crystals, with their edges rounded off; and has 

 the colour and shining look of bees'-wax 

 fig. 81). Small portions broken off are semi- 

 transparent ; an ammoniacal solution gives 

 thin lamellar hexagonal crystals by evaporation. 



Fig. 81. 



the oxalate is present in the form of exceedingly 

 minute crystals ; it then resembles a series of 

 minute cubes, often adhering together like 

 blood-discs : these, however, are readily and 

 distinctly resolved into octohedra under a higher 

 magnifying power. If the crystals be collected 

 and ignited on platinum foil, oxalic acid is de- 

 composed and carbonate of lime left : the sub- 

 sequent addition of dilute nitric acid dissolves 

 the residue with effervescence." The crystals 

 are insoluble in boiling acetic acid or liquor 

 potassae. 



Dr. Bird describes certain dumb-bell shaped 

 crystals {Jig. 80,6) with finely striated surfaces, 

 as a variety of form of oxalate of lime. We 

 have frequently seen such bodies, but cannot 

 regard their chemical nature as established. 



From a table, which we have drawn up from 

 the daily record of 84 unselected cases (42 of 

 each sex) in our wards at University College 

 Hospital, the following inferences may be drawn 



* On Urinary Deposits, p. 123. 1844. 



Pure cystin calculus, (long diameter nearly 2A inches, 



short ditto If.) Univ. Coll Mus. 



a, external surface ; b, section. 



Foreign to the natural constitution of the 

 urine, cystin is of very rare occurrence as a 

 morbid precipitate. It appears as a pale nearly 

 white pulverulent matter, insoluble in water, 



