STRUCTURE OF THE BONES. 21 



substance of the bones, is of a fibro-laminated nature, the 

 fibres in some parts being so closely aggregated, as to form a 

 compact bone, and separated and expanded in others, so as to 

 constitute the cells of the spongy portion. The longitudinal 

 fibres are much the most numerous, one leaning against, and ter- 

 minating near the commencement of another, so as to give an 

 imperfect appearance of continuity throughout the bone. 

 These fibres at the extremities of the bones, are lost in the 

 spongy or cellular tissue which they assist to form. The 

 transverse and oblique,* serve to connect the longitudinal fibres 

 together, and are united with them uninterruptedly upon their 

 sides ; in the spongy portions, they appear also, to assist in the 

 formation of the cells. They are both most abundant in early 

 infancy, and as the bones increase in length, are directed more 

 in the axis of the bone, till the oblique seem nearly lost in the 

 longitudinal, and the transverse become more oblique. 

 The fibres of the different layers of the compact bone, are 

 united to one another more intimately upon the sides, than to 

 the layers below, hence a bone exposed to the action of the 

 weather or the fire, shells off in scales, or in certain morbid 

 states during life, as necrosis, exfoliates in layers.f 

 From these investigations the osseous tissue, may be justly 

 considered as formed of an animal or membranous basis, analo- 

 gous to the common cellular tissue and cellular fibre in other 

 parts of the body, and differing from them only in its being imbued 

 or incrusted with inorganic earthy matter, which gives it ^firm- 

 ness and strength, but at the. same time renders it liable to 

 fracture. The cells of the bones, like those of the cellular tissue ^|*. 

 of the soft parts of the body, are all imperfect, having openings 

 by which they communicate with one another, and may be all 

 readily injected, with any fluid sufficiently thin to run ; and if 



* 



* These represent the uniting pins of Gagliardi. 



| Mr. Howship of England, from some recent microscopical observations on 

 the bones, has been led to support the opinion of Scarpa, that the ultimate tissue 

 of all the bones, is reticular or cellular. This is evidently true, in regard to the 

 ultimate analysis of bones, when the course of the fibres has been destroyed by 

 prolonged maceration, or by suppurative inflammation. p. 



