OF STONY CONCRETIONS. 523 



According to Sir Ev. Home, pus has for its use to furnish, 

 by its coagulation on the surface of suppurating wounds, the 

 materials of the cicatrix, that is to say, the organizable matter 

 of this new tegument. 



SECTION II. 



OF STONY CONCRETIONS. 



824. Concretions or calculi* are solid bodies, more or less 

 hard, wliich form -in the humours contained in the cavities, 

 the reservoirs, and the ducts lined with the mucous mem- 

 brane. This formation is always accompanied by a change of 

 composition more or less evident of the fluids where it takes 

 place. 



825. Intestinal calculi are rare in the human species. 

 These calcul-i, more or less voluminous and numerous, are 

 round or ovoid, yellow or brown: their specific gravity is 1.4. 

 Their nucleus is a biliary calculus, hardened faeces, or a fo- 

 reign body. They are formed of layers, and composed of 

 earthy substance, especially phosphate of lime, and a little 

 animal substance. 



The mucous and sebaceous follicles contain sometimes indu- 

 rated or more or less concrete masses. 



Several instances have been cited of little calculi of phos- 

 phate of lime and animal matter, in the caruncula lachryma- 

 lis, in the tonsils, and in the prostate. 



Stony concretions of the same nature have been found some- 

 times in the lachrymal canal and sac, in the salivary glands 

 and their ducts, and in the pancreas. 



826. The biliary passagest are frequently the seat of cal- 



* Walter, de concrementis terrestribus. Berol., 1775. Vicq. d'Azyr, Jlca- 

 dem. roy. de medicine, ann. 1779. Mosovius, Dissert, de cakulorem anima- 

 lium, corumque imprimis biliariorum origine et natura. Berolini, 1812. * 

 f Soemmering, de Concrementis biliariis carp, humani^ Traject. ad Moen., 

 1795. Thenard, Mem. de la Soc. d'Arcueil, vol. i. 



