STRUCTURE AND COMPOSITION OF BONE. 165 



sensitive; since unequivocal signs of pain are manifested by an animal, when, 

 a bone having been sawn across, a probe is passed up the cavity, or an acrid 

 fluid is injected into it. 



196. The ultimate substance of Bone, lying between the lacuna? and cana- 

 liculi, appears to be usully granular ; the granules are stated by Mr. Tomes* 

 to be often distinctly visible without any artificial preparation, in the sub- 

 stance of the delicate spicula of the cancelli, when they are viewed with a 

 high power ; and to be made very evident by prolonged boiling in a Papin's 

 digester. They vary in diameter from l-6000th to 1-14, 000th of an inch ; 

 their shape is oval or oblong, often angular; and they cohere firmly together, 

 possibly by the medium of some different material. Their own substance, 

 however, appears to be perfectly homogeneous ; but it is made up of several 

 components, as appears from the following statements regarding the chemical 

 composition of Bone. 



a. When the Calcareous matter of Bone has been dissolved away by the action of an acid, 

 the Animal substance which remains is almost entirely dissolved by a short boiling in water; 

 yielding to it a large quantity of Gelatine. This, indeed, may be obtained by long boiling 

 under pressure, from previously-unaltered Bone; and the calcareous matter is then left almost 

 pure. The Lime of bones is, for the most part, in the stale of Phosphate, especially among 

 the higher animals; it is curious, however, that in callus and exostosis, there is a much larger 

 proportion of Carbonate of lime, than in the sound bone; in which respect these formations 

 correspond with the bones of the lower animals ; but in caries, the quantity of the carbonate 

 is much smaller than usual. The composition of the Phosphate of Lime in Bones is peculiar ; 

 8 equiv. of the base being united with 3 of the acid. According to Prof. Graham, it is to be 

 regarded as a compound of two tribasic phosphates ; namely, 2 Ca, 0, H O, P O 5 -j-2 (3 Ca 0, 

 P O 5 ) ; with the addition of an equiv. of water, which is driven off by calcination. The fol- 

 lowing are the results of some of the most recent and careful analyses of Human Bone, by 

 Marchand and Lehmann : those of the former were made on the compact substance of the 

 femur of a man aged 30 ; and those of the latter on the long bones of the arm and leg of a 

 man of 40 years of age. 



Organic matter. MAHCHAND. LEHMANIT. 



Cartilage insoluble in hydrochloric acid . . . 27'23 } 

 Cartilage soluble in hydrochloric acid . . . 5-02 > 32-56 



Vessels . 1-01 ) 



Inorganic matter. 



Phosphate of lime 52'26 > ,. 



Fluoride of calcium . . . . . . 1-00 



Carbonate of lime 10-21 



Phosphate of magnesia ..... 1-05 



oda -92 



Chloride of sodium 0-25 



Oxide of iron and manganese, and loss . . 1'05 



100-00 100-00 



b. According to Dr. Stark,f the relative proportions of cartilaginous and earthy matter, in 

 the bones of different animals, in the bones of the same animals at different ages, and in the 

 different bones of the same body, never depart widely from the preceding standard; the 

 amount of earthy matter being always found to be just double that of the cartilaginous basis, 

 when the bones have been carefully freed from oily matter, and completely dried, previously 

 to the analysis. The hardness of bone, he maintains, does not at all depend upon the pre- 

 sence of an unusually large proportion of earthy matter; nor does their increased flexibility 

 and transparency indicate a deficiency of the mineral ingredients ; for the transparent readily- 

 cut bones of fish contain the same amount of earthy matter, in proportion to their gelatinous 

 basis, as do the dense ivory-like leg-bones of the deer or sheep. The same holds good of 

 the bones even of the so-called Cartilaginous Fish. The difference seems to depend upon 

 the molecular arrangement of the ultimate particles ; and especially, it seems likely, upon 

 the relative amount of water which the bones contain. 



Todd and Bowman's Physiological Anatomy, p. 108, and Cyclopaedia of Anatomy, art. 

 Osseous Tissue. 



f Edinburgh Med. and Surg. Journal, April 1845. 



