16 OSSEOUS TISSUE. 



incinerated and crushed bone, and he considers it not improbable 

 that the true osseous tissue, or the matrix of bone, consists 

 entirely of an intimate admixture of granules firmly combined with 

 one another. If this supposition should be confirmed by further 

 investigations, we could hardly conceive a juxtaposition of these 

 granules without an intervening substance : and even if this view 

 regarding the minute structure of osseous tissue should not be con- 

 firmed, the granular appearance would always militate against the 

 homogeneity of osseous tissue. 



The chemical, like the physical relations of osseous tissue, indi- 

 cate that in the minutest particles of it there is a very intimate 

 blending of the textural elements, but not a true mixture (or 

 chemical combination) into a homogeneous substance. It may be 

 inferred from the results of Hoppers experiments, to which we 

 have previously referred, that the bone- corpuscles and their pro- 

 longations are invested by an albuminous membrane insoluble in 

 boiling water. 



Further, it is an old-established fact that almost all the earthy 

 constituents may be extracted by dilute acids from a bone, without 

 affecting its form, or even destroying its minute structure ; in the 

 same way the form and structure of a bone remain unchanged 

 when we remove the organic matter from it, either by calcination 

 or by careful boiling with dilute alkalies. These two facts might 

 at first seem to be in favour of the view that the osseous tissue is 

 homogeneous, and that there is an actual chemical combination 

 between its organic and inorganic matters ; but when we consider 

 that the very numerous analyses of bone which have been already 

 published do not lead to the inference that there is a definite pro- 

 portion between the organic and inorganic matters, but on the 

 contrary, that the proportions vary extremely in accordance with 

 the physiological conditions, and further, when we bear in 

 mind that the cartilage may be removed from bone even by the 

 weakest agents, as for instance, by boiling with water in a Papin's 

 digester, or by an extremely dilute solution of potash, we feel at 

 all events that we have grounds for doubting that the matrix of 

 bone is a chemical compound of earthy and organic matters ; and 

 we are strengthened in these doubts by observing that the minute 

 points grow pale or entirely disappear in osseous substance treated 

 with dilute hydrochloric acid. 



As we have already spoken, in the first volume, of the indi- 

 vidual constituents of osseous substance, we need here only observe 

 in reference to its qualitative composition, or rather, in reference to 



