OF THE BONES. 383 



605. Accidental ossification* is of very frequent occur- 

 rence, and was known at a very early period. This ossifica- 

 tion is rarely perfect, and may in this respect be distinguished 

 into several varieties. 



The least perfect kind of accidental ossification is called 

 earthy. It produces a white, opaque, chalky, soft, friable, and 

 even sometimes semi-fluid substance. It is composed of ani- 

 mal matter, in small proportion, and earthy substance, and is 

 commonly met with in cysts. Phlebolites are sometimes 

 of this kind. It also occurs in isolated and formless fragments, 

 in abscesses, in the lungs, in the fibrous body of the uterus, in 

 the cellular tissue, and in the ligaments of persons affected 

 with gout, in the brain, &c. Lastly, it is frequently met with 

 infiltrated in the bronchial glands, the lungs, the liver, the 

 kidney, the heart, &c. 



The stony accidental ossification is of very frequent occur- 

 rence. It is very hard, opaque, and contains a greater pro- 

 portion of earthy substance than the bones in their natural 

 state. It is often met with under the form of a more or less 

 thick incrustation under the serous membranes, in the proper 

 membrane of the spinal marrow, and especially in the walls 

 of the arteries. It also occurs under the form of cysts. It is 

 observed under the form of isolated masses in the fibrous bodies 

 of the uterus which have been ossified, and in the pineal gland, 

 where it constitutes the substance called acerbulus. It is also 

 sometimes met with under the form of infiltration of the pan- 

 creas. What has been described under the name of petrifac- 

 tion of certain organs, or of the foetus, is nothing else than an 

 infiltration of very compact stony bone, so as to cause the ani- 

 mal matter of the organ to disappear almost entirely. 



The accidental production sometimes differs still more from 

 the bones, resembling in hardness and polish the enamel of 

 the teeth. This accidental enamel sometimes replaces certain 

 diarthrodial cartilages. 



Accidental ossification sometimes greatly, or entirely, re- 



* J. Van Heckeren. De osteogenesi pr&ternaturaK. Lugd. Bat. 1797. 

 P. Rayer. Mem. sur F ossification morbidc, in Archives Gtntr. de M?d. t. i, 

 Paris, 1823. 



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