Bone. 71 



BONE. 



PREPARING HARD BONE. 



Bone must be examined in two forms, first in its dry 

 state, and secondly when it has been decalcified or had 

 its earthy salts removed. In the case of dry bone a very 

 few sections will suffice as it is a difficult and laborious 

 task to get them well made. 



The bone is fixed in a vice and sections as thin as 

 possible are cut with a fine saw, these are rubbed down 

 with fine emery on a stone, and finally polished on a 

 hone ; they must be well washed to remove all debris 

 and are better mounted dry, as they are apt to become 

 too transparent when mounted in glycerine or other 

 media. 



DECALCIFYING BONE. 



It is a very different matter to make sections of a 

 bone after the earthy salts have been removed, as it 

 can be cut, as easily as any other tissue, with the freez- 

 ing microtome or razor. 



To macerate small bones, such as mouse tail, half per 

 cent, chromic acid will be sufficient ; they should not be 

 left in too long. Larger bones must be cut into small 

 pieces and placed in half per cent, solution of chromic 

 acid for a week or ten days, and then one-twentieth of 

 the volume of hydrochloric acid added to the original 

 fluid. First harden then soften them, five or six days 

 after the addition of the acid will be enough according 

 to the size of the bones. They should then be tho- 

 roughly washed in water for several days or a week, 



