THE OSSEOUS SYSTEM. 320 



origin to the "loose cartilages," as they are termed; they do 

 this by their increasing in size and solidity, and becoming 

 detached from the vascular folds. Tliese bodies are also met 

 with, in mucous bursa} and the sheaths of tendons, which are 

 also furnished with vascular folds (vid. sup. § 82); they consist 

 of connective tissue with elongated nuclei, coated with epithe- 

 lium, and, though not always, contain a variable number of 

 scattered fat- and true cartilage-cells ; and they are not deve- 

 loped externally to the synovial membrane, but from an out- 

 growth of that membrane itself. Similar solid bodies, more- 

 over, may probably be produced in other ways ; Bidder 

 ('Zeitsch. f. rat. Medicin./ vol. iii, p. 99, et seq.) at all events, 

 and Virchow ( c Med. Zeitung/ 1846, Nos. 2 and 3) have 

 observed similar bodies presenting no trace of organization. I 

 am inclined, with Virchow, who has actually demonstrated the 

 presence of fibrin in them, to regard them, in many cases, as 

 fibrinous exudations, and in others as solidified deposits from 

 the synovia, which latter supposition is supported by the 

 frequent occurrence of curdy, more or less consistent, struc- 

 tureless masses, evidently iuspissated synovia, in the tendinous 

 sheaths of the hand. Portions of bone, also, detached from 

 outgrowths at the circumference of the articular ends of the 

 bones, may find their way into the interior of the articulation. 

 The plicce adiposa have perhaps less to do with the formation 

 of the synovia, than with the mechanism of the joint, serving 

 the purpose of filling up hollows.] 



§ 97- 

 Physical and chemical properties of the Bones, and their 

 accessory Organs. — The bones are composed, besides a small 

 quantity of water (3 — 7^, according to Stark in the compact 

 substance), and fat (2 — 3£ Bibra), principally of a substance 

 affording gelatine, and of inorganic elements. The latter, in the 

 adult, constitute two thirds (68 - 82 Bibra) of dry bone, and are 

 nearly all left when the bone is calcined; in which case, if due 

 care be taken, the bone completely retains its external aspect, 

 although it may be readily reduced to a white, opaque, friable, 

 heavy powder, the so-termed "bone earth." This consists 

 chiefly of 57 — 59£ basic phosphate of lime (according to Heintz, 

 3 atoms base, 1 atom acid), of carbonate of lime (7 — 8||) and 



