OF ACCIDENTAL TISSUES. 525 



They are sometimes homogeneous, frequently formed of 

 superimposed layers, similar or different; at other times mix- 

 ed or heterogeneous, and without layers. 



The calculi of the bladder are composed: 1st, of uric acid; 

 2d, of cystic.oxide; 3d, of phosphate of lime; 4th, of urate of 

 ammonia; 5th/ of ammoniaco-magnesian phosphate; 6th, of 

 oxalate of lime; 7th, of silex; Sth, of carbonate of lime; 9th, 

 of xanthic oxide; 10th, of fibrinous matter; llth, of mucus; 

 and 12th, of phosphate of iron, and magnesia, of carbonate of 

 magnesia, and urate of soda. These substances are found in 

 calculi, either isolated or combined by two, three, four, and 

 five. The most common of all is the calculus of uric acid; 

 then the fusible calculus, composed of the ammoniaco-magne- 

 sian and calcareous phosphates; then the mural calculus, com- 

 . posed of oxalate of lime; then the calculus formed of distinct 

 layers of uric acid and of oxalate of lime, &c. Silex and the 

 cystic oxide, and still more the xanthic oxide and fibrine, are 

 the rarest substances in urinary calculi. 



828. It is said that pisiform calculou* concretions have 

 been found in the spermatic vesicles and ejaculatory ducts. 



Similar little concretions are sometimes found also in the 

 fallopian tubes. As to concretion^ in the uterus, these are for 

 the most part ossified fibrous bodies. However, concretions 

 of phosphate of lime have been found in this organ having a 

 foreign body for a nucleus. 



We are assured that calculous concretions have been found 

 in the excretory ducts of the nipple. 



SECTION III. 



OF ACCIDENTAL TISSUES. 



829. Accidental tissues* are new organs developed in the 

 living body. 



* Laennec, Cours oral de medecine, au College de France, annte 1820-1823. 



