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PHYSIOLOGY FOR BEGINNERS 



the outer circles or lamella?. These minute canals or 

 canaliculi, as they are called, supply channels by which 

 nutrient fluid exuding from the blood-vessels in the Haversian 

 canal can pass from the Haversian canal to the bone 

 immediately around to nourish it, the bone being made up in 

 this way of a number of Haversian systems. 



A Decalcified Bone. A bone is hard, owing to the 

 presence in it of mineral matter. If a bone is allowed to soak 



FIG. 28. Transverse section of bone. Highly magnified. 

 H, Haversian canals ; /, lacuna: with canaliculi. 



in acid for a few days it loses its hardness and becomes soft 

 and flexible, although it retains its original shape. Such a 

 bone has had the earthy salts dissolved out of it, and is said to 

 be decalcified. If a fresh bone be treated in this way and then 

 a thin section of it be examined, the Haversian systems will be 

 seen as before, and in each lacuna will be a small cell, a bone 

 corpuscle, as it is called, containing a nucleus, and the 

 cell substance having fine processes going for some distance 



