438 



BONE, PATHOLOGICAL CONDITIONS OF. 



opinion exist on this point. Even Berzelius 

 expresses a doubt whether magnesia is met 

 with as a phosphate or a carbonate. We find 

 iron mentioned by Fourcroy and Vauquelin as 

 present in bone. This, according to Berzelius, 

 depends on the red blood which its vessels 

 happen to contain. They also mention silica, 

 alumina, and phosphate but no finale of am- 

 monia. 



4. Its peculiarities in other animals. In 

 the course of this article we have noted the 

 most striking of those peculiarities, so that 

 little need be said under the present head. 



The Radiata, Articulata, and Mollusca 

 have coverings which somewhat resemble bone, 

 and are considered by some physiologists as the 

 osseous system of these classes. This opinion 

 will be examined in another place. 



Fishes. Cartilaginous fishes have very little 

 earthy matter in their skeleton, so that their 

 bones scarcely deserve the name. They are very 

 flexible, elastic, homogeneous, and semi-trans- 

 parent, and in chemical composition resemble 

 inspissated mucus. Osseous fishes have bones 

 properly so called. They are more flexible 

 than in the higher classes, have no medullary 

 cavity, little of the spongy tissue, and make 

 no approach to the laminated arrangement. 



Amphibia have no appearance of laminae in 

 their bones, nor, with the exception of the 

 crocodile, a medullary cavity. In chemical 

 composition they resemble those of fishes. 



Birds have firm, elastic, and thin bones, 

 shewing less of the cellular and more of the 

 laminated disposition than we meet with in the 

 other classes. They have large and well deve- 

 loped cavities, which contain air instead of 

 medulla. 



Mammalia. The bones of the cetacea are 

 coarse and fibrous externally. Within they are 

 spongy or cellular, but the cells assume a re- 

 markable tubular disposition. There is no 

 medullary canal. The bones of quadrupeds 

 do not differ much from those of man. In 

 general they are of a coarser texture, and in 

 some, as in those of the head of the elephant, 

 we find very extensive air-cells. 



BIBLIOGRAPHY. Leuwenhoeck, Microscop. Obs. 

 in Phil. Trans. 1674 and 1678. Malpighi, De 

 ossium structura, in Ej. Anat. Plantar, tol. Lond. 

 1675, et in Ej. Op. Posth. Venet. 1743, Lond. 1697. 

 Havers, Osteologia nova, 8vo. Lond. 1681. Gayli- 

 ardi, Anatome ossium, 8vo. Lugd. Bat. 1723. 

 De La Seine, Mem. i. et ii. sur 1'organization des 

 Os. Mem. de Paris, 1751. Albinus, De construc- 

 tione ossium, in Annot. Acad. lib. vii. Scarpa, 

 De penitiori ossium structura Com. 4to. Lips. 1799 : 

 4to. Paris, 1804 ; Ticin. 1827, s. t. : De anat. et 

 pathol. oss. Malacarne, Auct. ad osteologiam, &c. 

 Ludwigii et Scarpae, Padov. 1801. Caldani, Mem. 

 sulla struttura della ossa umana e bovina, 4to. 

 Padov. 1804. Hows/tip, Microscopic observations 

 on the structure of bone, in Med. Chir. Trans, 

 vol. vii. Medici, Esperienze intorno alia tessitura 

 organ, delle ossa, in Opusc. Scientif. t. ii. Bologna, 

 1818. Speranza, Consid. sul. tessitura organ, delle 

 ossa, Bolog. 1819. Ilmoni, Physiol. syst. oss. 

 spec. i. et ii. 4to. Aboae, 1825,-6. See also the 

 various systems of general and descriptive anatomy 

 and of physiology, and further in the Bibliography 

 of OSSEOUS SYSTEM and OSTEOGENY. 



(Charles Benson.) 



BONE, PATHOLOGICAL CONDI- 

 TIONS OF. The bones, as the foundations of 

 the animal system, as the passive organs of loco- 

 motion, required necessarily to be firm and com- 

 paratively inelastic and unyielding, qualities 

 which we have seen in the preceding article are 

 imparted to them by the addition to their original 

 animal elements of a saline or earthy substance, 

 consisting principally of phosphate of lime. 

 It is obvious that this difference of structure 

 and constitution must have considerable in- 

 fluence in modifying the diseases to which 

 they are liable, and in giving to the affections 

 of these organs many of their distinguishing 

 peculiarities. In considering, therefore, the 

 phenomena exhibited in the various patholo- 

 gical conditions of the osseous system, not 

 only must the presence of this unorganized 

 earthy substance be constantly borne in mind, 

 but even its relative amount, its abundance or 

 deficiency must command attention. In early 

 life, when the animal material preponderates 

 in quantity, the bones are highly vascular, and 

 comparatively soft, flexible, and springy, and 

 though liable to many serious diseases, they 

 are very apt to escape the effects of injury : 

 fracture is uncommon in infancy; and in child- 

 hood the bones, bending rather than breaking, 

 often exhibit that partial fracture which has 

 been likened to a " branch of a tree that 

 yields to an attempt to break it while it still 

 retains its sap."* The powers of repair are 

 commensurate with the extent of vascular or- 

 ganization at this period; fracture is quickly 

 re-united, and its effects so regulated by the 

 subsequent growth of the bone that permanent 

 deformity is a very infrequent occurrence. 



But this activity in the osseous system in 

 early life has its evils. The period of youth, 

 between absolute childhood and puberty, is 

 that in which disease is most easily and, there- 

 fore, most frequently developed, and although 

 extensive powers of reparation are constantly 

 exhibited in recovery after caries, in re- 

 production after necrosis &c., still are the 

 operations that lead to these results languid 

 and too often inefficient, circumstances that 

 may be attributed partly to peculiarity of or- 

 ganization in the structure affected, but per- 

 haps with more propriety to the influence of 

 some general constitutional taint over which 

 medicine exerts but slender control. 



The osseous system cannot be considered as 

 having attained maturity until a period sub- 

 sequent to the age of puberty, most commonly 

 somewhere between the twenty-seventh and 

 thirtieth years. At this time bone is calculated 

 most perfectly to answer its purposes in the 

 animal economy : it is then least liable to 

 disease; and if fractures and other injuries 

 are more frequent, it is only because indivi- 

 duals are now more exposed to them. The 

 effects of these injuries are in general repaired 

 sufficiently well, but if deformity has been 

 produced it will be permanent, because the 

 bone has ceased to grow. 



* See a paper on this subject by Dr. Hart, vol. i. 

 Dublin Journal of Medical Science. 



