76 



PRODUCTS, ADVENTITIOUS. 



word implies, composed of successive layers. 

 Although each layer may and generally does 

 differ in thickness from others, its own thick- 

 ness at its different parts may be said to be 

 commonly pretty uniform ; nevertheless to this 

 there are exceptions, and it is manifest that 

 whenever the cause of accretion is in greater 

 activity towards one aspect of a calculus than 

 another, there the lamina in course of deposi- 

 tion must be thicker than elsewhere. Now in 

 conformity with a general principle already laid 

 down, we should expect the phosphates, which 

 are formed in consequence of local irritation 

 in particular places, to furnish the most fre- 

 quent instances of irregular thickness ; and 

 such is in truth the fact, though, as is proved 

 by the annexed cut (fig- 75), not always so. 



Fig. 75. 





wiitefe 



lSj^c>-;f> ^? .<// 



5 ? 



almost constantly occurs in calculi, and some- 

 times forms the nucleus of a mass. Howship 

 has figured a remarkable specimen, voided 

 from the urethra of a negress, in which the 

 nucleus consisted of "mucus," associated with 

 a very little phosphate of lime, the cortex of 

 more solid phosphates. Clots of blood occa- 

 sionally form the central part of calculi ; a fact 

 noticed first by Frere Come. 



Thirdly: foreign bodies, introduced from 

 without, not very unfrequently constitute the 

 nuclei of urinary calculi. In the great majority 

 of cases these bodies are directly pushed into 

 the bladdur ; but in some well-authenticated 

 cases have reached that viscus after having been 

 swallowed or otherwise introduced. Among 

 bodies acting as nuclei have been met pins 

 (Univ. Coll. Mus.), needles, tooth-picks, ear- 

 picks, pieces of wood, stems of plants, ears of 

 corn, grains of corn, stones of various fruits, 

 tubes of various kinds, glass or earthen, &c., 

 pieces of bougies and catheters, balls and other 

 metallic bodies, a globule of mercury,* pebbles, 

 &c. When the bodies thus introduced are 

 sharp, as pins, they sometimes protrude beyond 

 the calculous matter, and (a fact surgically im- 

 portant), are fixed in the surrounding tissues. 



Instead of a nucleus the centre of a calculus 

 may present one or more cavities of variable 

 size and shape, almost invariably lined with 

 a black pulverulent or laminar matter, and 

 sometimes containing powdery substance; in 

 other instances, there is neither surrounding 

 nor contained matter of this kind. It has 

 been supposed that in all these cases an origi- 

 nal vegetable or animal nucleus had been 

 gradually removed by a process of decom- 

 position and subsequent filtration through 

 chinks in the cortex. 



The prominent physical characters of the 

 cortices of calculi divide them into two na- 

 tural classes ; the () granular or irregular, and 

 the (ft) laminated. 



(a) Of granular calculi the best example is 

 supplied by oxalate of lime, but the appear- 

 ance of these masses is not always identical. 

 Sometimes the mass looks homogeneous and 

 non-granular, manifestly from the close aggre- 

 gation of the original granules. In the more 

 ordinary cases the granules remain d'stinct, 

 whence the well-known tuberculated or mul- 

 berry-like aspect. Uric acid calculi, rendered 

 impure by association of certain saline matters, 

 assume the granular form ; the phosphates are 

 sometimes granular; and the pulverulent cha- 

 racter of the fusible calculus allies it to this 

 species. 



(ft) In laminated calculi the cortex is, as the 



* See Malago, in Filiatre Sibezio, 1845 ; or Si- 

 mon's Chemistry, by Day, vol. ii. p. 440. In the 

 University College Collection is a triple phosphate 

 calculus, having the tibia of a foetus for its nucleus. 

 The pregnancy had been Fallopian, and ulceratiou 

 having occurred between the adherent tube and the 

 bladder, the tibia (with probably other portions of 

 the skeleton subsequently otherwise disposed of,) 

 made its way into the latter organ, and became en- 

 crusted abundantly 'with phosphates. The calculus, 

 presented to the College by Mr. Liston, was given AJ/ernatintj calculus nfuric acid and [.?] trifikphos- 



O.ralate of lime nucleus; the cortex (circular and 

 conoid parts) impure uric acid, ( U. C. Museum ; 

 patient of Mr. Quain.) The spherical part was 

 probably seated in a succulus. 



The mode of union of the laminas differs ; it 

 may be so intimate that the line of separation 

 is lost at certain points of the apposed sur- 

 faces ; in other cases the union is imperfect 

 and loose, and interspaces of some width are 

 left between those surfaces. 



The section of a laminated calculus is some- 

 times marked by lines radiating from the centre 

 to the periphery, cutting the laminae into seg- 

 ments of unequal size. This is obvious in 

 certain cystin calculi, in some of uric acid, and 

 in many of the mulberry species. 



The tint of the different strata of a calculus, 

 composed essentially of one substance, is not 

 always the same throughout ; nor are strata, 

 the same in composition and separated by ma- 

 terials of other kinds, generally of the same 

 hue. These varieties must depend upon 

 irregular admixture of impurities. 



Calculi composed, at least essentially, of a 



Fig. 76. 



to him by Dr. D. R. Lietch. 



jilmtc. (University Cottege Museum.*) 



