848 



OSSEOUS TISSUE. 



Fig. 448. 



. '",-- 



Transverse section from the dense portion of the femur. 



a, Haversian canal ; b, concentric laminae ; c, laminae of connection ; 

 d, corpuscles, with their system of tubes. 



The parts marked a, b, and d constitute an Haversian system. The 

 figure includes three systems with laminae of connection uniting them. 



lected, it will be found to contain no Haversian 

 canals or corpuscles, but to be extremely thin 

 and transparent. Such a portion, when viewed 

 with the one-eighth of an inch object-glass of 

 Mr. Powell's microscope, will present a deli- 

 cate granular aspect with the surface nodulated. 

 This granular appearance arises from the sub- 

 stance of the bone being composed of minute 

 irregularly spherical granules. It is not diffi- 

 cult to trace this structure in any specimen of 

 bone, though in some it is much more distinct 

 than in others. Specimens put up in Canada 

 balsam do not show the minute structure very 

 well. It is best to place the object between 

 two slips of glass with a little plain water. 



A delicate spicula from the point where os- 

 sification is going on is usually very good for 

 illustrating the granular tissue. 



But the granules may be obtained separated 

 from each other, so that each individual may be 

 examined apart from its fellows. When so 

 exposed to view, they exhibit a tolerably re- 

 gular character, being mostly spherical, some 

 few having an oval form. In some specimens 

 the oval predominates over the spherical con- 

 formations. Often a few will be found which 

 are egg-shaped, with the smaller end elongated, 

 (see fig. 449,) though to no great extent. The 

 osseous granules may be gained by subjecting 

 bone to high-pressure steam, or to a red heat, 

 till all the animal matter is removed. In either 

 instance the granules may be obtained by taking 



!. 449. 



Ultimate osseous granules obtained by depriving the 

 bone of its animal matter. 



a small portion of the so treated bone, satura- 

 ting it with water, and then gently reducing it 

 to a powder between the slips of glass. By this 

 manipulation the granules individually will be 

 rendered evident when the specimen is exa- 

 mined under a high power. But, by the break- 

 ing down of the mass, many granules are neces- 

 sarily broken; to remedy this imperfect and con- 



