190 NON-INFLAMMATORY DISEASES OF BONES. 



readily detached, does not come away with so much fticility as 

 from the bones of the head, except towards the ends of the bones, 

 where, strange to say, the ligaments had become detached by the 

 mere movements of the animal during life. The outer surface of 

 the shaft of the bone is firm enough, but on section it is found 

 to be greatly thinned, in consequence of an enlargement of the 

 medullary canal having taken place at the expense of the osseous 

 structure. 



" The dilatation of the medullary cavity is most marked 

 towards the extremities of the bone, and there the marrow is 

 deeply tinged with blood. The osseous tissue, which in some 

 parts is reduced to one-half, or even one-third of its normal 

 thickness, does not present the spongy appearance of the cranial 

 bones, but, on the contrary, is dense, and so hard that it cannot 

 be cut with a knife. 



" After the calcareous matter is removed by acid, the section 

 of the animal matter has a somewhat glistening cartilaginous 

 appearance, here and there dotted with opaque white spots. 

 Under the microscope, a thin section reveals a curious condition 

 of tilings ; the Haversian canals, as well as the concentric bony 

 lamellse surrounding them, appear perfectly normal. The lacunse 

 and canaliculi, as far as can be ascertained in the decalcified 

 bone, are equally healthy ; but, on close inspection, the opaque 

 white spots observed by the naked eye are seen to be irregu- 

 larly shaped cavities in the osseous tissue, filled with fat cells. 

 These cavities vary in size, from that of a pin's point to a millet- 

 seed. They are not limited to any particular portion of the 

 osseous structure, although they seem to have commenced, for 

 the most part, in the lacunse. Some, however, may, with equal 

 truth, be said to have originated in the Haversian canals, the 

 walls of which have been gradually broken down and eaten 

 away, as the morbid condition advanced ; the place of the 

 earthy and animal matter being gradually taken up by fat 

 corpuscles." 



Professor Yarnell says, in continuation of his most admirable 

 description, that " the bones, after being macerated and dried, 

 exhibited many peculiarities which were not apparent in their 

 fresh state ; for instance, the ulceration of the articular surfaces, 

 which seemed to be altogether confined to the cartilages of 

 incrustation, was found on their removal to affect the bone 



