(71 







671 



force* applied transversely, that is, tending to break the cylinder 

 acram ; it ha* been often stated that a given quantity of material* 

 couM not po*ibly have been dispoaed in a manner better calculated 

 for inch reactance than thow in the form of a tube or hollow 

 . ylinder. The hollow steins of vegetables derive their chief strength 

 from [irNiiimiing this form. Bone* akw are rendered both lighter 

 and stronger by IMMI>K imide hollow than if the cylinder had been 

 olid ; and as it is in the middle of the shaft that the strain is 

 greatest, so it is here that the cavity is largest and the resistance most 



Bone has been recently submitted to rigid chemical analysis, and 

 the result is that in healthy bone about two-thirds, or 667 per cent, 

 consist of saline or earthy matters, and 33-3 per cent, or one-third, 

 of animal matter. The bones of children contain more animal matter, 

 and of aged persons more earth. Different bones aim in the same 

 skeleton contain different proportions of these constituent* Thus, 

 according to Dr. O. O. Rees, the bones of the head and the limbs 

 contain more earth than those of the trunk. The following are two 

 ultimate analyses of bone from Dr. Sharpey's Introduction to ' Quain's 

 Anatomy :' the one is by Berzelius, the other by Mr. Middleton of 

 University College: 



Bcnelius. Middleton. 



Animal Matter 83-30 33'43 



Phosphate of Lime 51-04 6M1 



Carbonate of Lime 11-30 10-31 



Fluoride of Calcium 2'00 1'99 



Magnesia, wholly or partially in the state") j.^g 1 ., ; - 



of a phosphate ) 



Soda and Chloride of Sodium . . . 1'20 1 '- 



The phosphate of lime in bones is peculiar, and is known amongst 

 chemists as the 'bone-earth phosphate.' It is what is called a 

 tribasic phosphate, consisting of 8 equivalents of lime, 3 of phosphoric 

 acid, and 10 of water. Fluoride of calcium is found in larger 

 quantities in fossil than in recent bones ; and such is its abundance 

 in some fossils, as those brought from the Sevalik Hills, in India, by 

 Dr. Falconer, that we must have recourse to the supposition of a 

 substitution of this substance for phosphate of lime, in order to 

 account for its presence. 



We have referred to the statement that the bones of the limbs 

 contain more earth than the trunk. The following analysis by 

 Lehmann shows that the bones of the arms and legs have a different 

 compostion : 



Ilumcrus. Femur. 



Phosphate of Lime and Fluoride of Calcium 56-61 68'93 

 Carbonate of Lime .... '20 9'28 



Phosphate of Magnesia 1-08 1-09 



Chloride of Sodium 0'37 0'40 



Bo& 1-35 1-04 



Organic Matter . . . . . . 31-52 28-61 



When examined under the microscope, sections of the different 

 bones present very different appearances, not at first easily reconciled 

 with a common mode of origin or growth. The result of a close 

 investigation, however, shows that the osseous tissue like all other 

 parts of the body originates in cells. This fact i not easily traced, 



f\g. 1. TraniTcrtt Section of the dense portion of the Frmur. 

 a, Ilaremlan Canali ; , concentric Utninir ; e, Uminir of connection ; d, cor- 

 puscles with their nyttem of tube*. The parts marked a, ft, and rf, constitute 

 an IIrerUn system. 



and we shall first speak Inn ,,f the appearance* presented on a 

 minute examination of the texture of the bone. 



The canals which are everywhere found traversing variously the 



substance of bone, and giving DM. age to the blood-Teasels for the 

 nourishment of the tissue, are called Haversian Canals, a name given 

 them in consequence of Clopton Havers having been the first who 

 gave a full account of them. The parietes of these canal* have a 

 laminated arrangement The lamina) themselves are numerous and 

 placed concentrically; the internal lamina, that which is in imme- 

 diate contact with the vessel or vessels, being tho most distinctly 

 marked, and each succeeding one having a less distinct outline. 



Besides the concentric lamina;, there are others which surround 

 the exterior of the bone, and may be known as the superficial latnino:. 

 In connection with both the concentric and superficial lauiime are a 

 third set, which cannot belong to either of the other orders, but 

 which are placed between them, and form the bond of union between 

 each system. 



Much has been lately written on the bone-corpuscle*. These are 

 small cells of oval form placed between the lamina;, and having 

 numerous distinct tubes running from them in almost every direction. 

 They have been sometimes compared to a spider with many legs. 

 The corpuscles, or as they are occasionally called the calcigerous 

 cells, have a definite relation to the Haversian Canals and to each 

 other. 



The Haversian Canals, the Osseous Lamina;, and the Bone-Corpuscle* 

 are therefore the leading points to be mentioned in treating of the 

 structure of the bone. Upon a closer view, however, it will be seen 

 that it is only the lamina; which are bone ; the canals and corpuscle* 

 are spaces existing in bone, and are not really necessary to the 

 existence of osseous tissue, though they are requisite where the 

 amount of substance is appreciable to the unaided senses. 



Of the Substance of Bont, or J/i/nliiic Xubttanct.The substance of 

 bone has been considered, with but one-or two exceptions, as homo- 

 geneous, and without appreciable structure. If it be examined how 

 ever under advantageous circumstances, with high magnifying | 

 there will be no difficulty in detecting a very definite though d' 

 structure. A very small portion of a thin plate of bone should be 

 taken for the purpose of examination : such may be found in the 

 ethmoid bone of small animals, as of the rat If the piece is pro]'i-ly 

 chosen it will be found to contain no Haversian Canals nor corpuscles, 

 but will be extremely thin and transparent A piece of this kind will 

 present a delicate granular aspect with the 

 surface nodulated. This granular appearance 

 proceeds from the substance of the bone being 

 composed of minute irregularly spherical 

 granules. This structure may be traced with- 

 out much difficulty in any specimen of bone, 

 although it varies much in distinctness in 

 different specimens. The object should be 

 placed between two slips of glass with a little 

 plain water for examination. A delicate 

 spiculum from the point where ossification 

 is going on illustrates the granular tissue ex- 

 ceedingly well. The granules may be obtained 

 Fig. 2. Ultimate os- separated from each other, so that each indi- 

 scous granules, obtained yjdual may bo examined independently of the 

 by depriving bore of it otherg when geen j,, y,;,, manner they exhibit 



a tolerably regular character, being mostly 



spherical, though a few have an oval form. In a few specimens the 

 oval form predominates. 



Of the Lamina. The form assumed by the osseous tissue is that of 

 i. rn'iTia-, and these lamina; have a definite arrangement, so much so 

 i hat three distinct systems are recognised, namely, lamina: of the 

 i an Canals ; secondly, the lamina: which connect the Haversian 

 systems ; and, thirdly, the lamina: which form the surface of the bone, 

 and inclose the two previous orders. The lamina) of the Haversian 

 Canals have a concentric arrangement, and when divided transversely 

 present a series of more or less distinct and perfect rings. They vary 

 very much in number, but the most common amount is ten or twel\ e. 

 Of these, the internal lamina, that which forms the pari. 

 Haversian Canal, is most distinctly marked, while each succeeding one 

 as we proceed outwards becomes less distinct Connecting these 

 Haversian systems is a second series of lamina;, without which the 

 former would exist but as a bundle of loose tubes (fig. 1, c). In this 

 substance we find the laminated arrangement less distill' t. t 

 regular, and the laminn: individually subject to great irregularity of 

 thickness. They are generally more transparent than cither tho 

 Haversian or external system. The last division consists of those 

 lamina: which surround the exterior of the bone. These have greater 

 individual extent, but are the least numerous. They arc continuous 

 with the lamina; of the Haversian system whenever the latter arrive 

 at the surface of the bone ; the external lamina: in this case being 

 continuous with the inner lamimc of the Haversian system. 



The effect of madder upon the osseous system, when given to an 

 animal with iU food, may here be noticed, since the colour is imparted 

 i" the lamina:. By introducing madder into the stomach, a deep red 

 tinge is very soon observed : in a pigeon the bones were rendered 

 brilliantly red in 24 hours. A similar effect was produced on a young 

 pig in three weeks. On making sections of bone so affected, the 

 colour is found to be present in the external lamina) of the bone, and 

 in the inner lamina; of the Haversian system, thereby proving that the 



