58 SKELETON. 



part by an acid. The cartilage thus left is the complete 

 mould, in every particular of form, into which the particles of 

 calcareous matter were deposited. In this state, the compact 

 part of the bodies of the cylindrical bones may be separated 

 into laminae ; and these laminae, by the aid of a pin or fine- 

 pointed instrument, may be subdivided into filaments or threads. 



The laminae, though enclosing one another, are not exactly 

 concentric. I have observed, that the more superficial come 

 off with great uniformity and ease in the adult bone, but the 

 intertexture continually increases towards the centre. Bichat 

 has objected to this dissection of the bones, that the laminae 

 are not formed in nature, but factitiously, by the art of the 

 anatomist, and that their thickness depends entirely on the 

 point at which one chooses to separate them ; they, therefore, 

 may be made thick or thin at pleasure. It does not appear to 

 me difficult to account for the manner in which this laminated 

 arrangement is produced. The longitudinal filaments of the* 

 bones adhere with more strength to each other at their sides 

 than they do to those above or below, in consequence of which 

 a plane of these filaments may be raised at any place and of 

 any thickness. This fact does not involve the inference that 

 the bones are formed by a successive deposite of one lamina 

 over another; it merely inculcates the mode of union between 

 the filaments or threads. I am, however, inclined to the opi- 

 nion that the periosteum secretes the externaF laminaB in the 

 adult bone, inasmuch as they separate with unusual facility 

 from the subjacent one. We know that the periosteum has 

 the power of this secretion, as a laminated deposite of bone on 

 the roots of the adult teeth frequently met with, proves without 

 doubt, as also the phenomena of necrosis. 



The disposition of the cylindrical bones to separate into 

 laminae, is constantly manifested in such as are simply exposed 

 to the atmosphere. 



The opinion of the laminated and filamentous arrangement 

 of bones has been very generally adopted by anatomists. 

 Malpighi, whose name is inseparably connected with minute 

 investigations in anatomy, taught it. Gagliardi, also, in ad- 

 mitting it, thought he saw pins of different forms for holding 

 the laminae together. Havers also saw the laminated and 

 thread-like structure. In short, there are few of the older 



