131 



82% alcohol. In fixing, structures not needed should be removed, — 

 muscles trimmed awaj' from the bone, etc. Bones or teeth should 

 be opened with nippers or a saw, so that the fluid may reach the 

 marrow or pulp cavity. 



Place the hardened tissue in the decalcifier, where it should 

 remain until the lime salts have been entirely removed, as may be 

 ascertained by inserting a fine needle ; if any calcified matter remains 

 there will be a gritty feeling on using the needle. The time neces- 

 sary for complete decalcification will depend upon the size and den- 

 sity of the calcified tissue, and will vary from 3 to 15 days or longer. 

 The decalcifier should be changed after the first day, and if the tis- 

 sue is large it is best to change it subsequently two or three times at 

 intervals of two or three days. 



When decalcification is complete rinse the tissue well in water 

 for a few minutes and place it in 6y% alcohol for one or two days 

 and then in 82% alcohol for several days, or until ready to imbed. 

 The 82% alcohol should be changed once or twice in order that the 

 nitric acid may be well washed out. Although paraffin in inany 

 cases may be employed for imbedding, the collodion method is gen- 

 erally more satisfactory. 



Hematoxylin with eosin, hematoxylin with picrofuchsin, and 

 hematoxylin with picrocarmine afford good stains ; by staining 

 thoroughly with hematoxylin a differential staining of bone and 

 cartilage may be obtained. 



(B). Sections of Dry Bone or Tooth. 



§ 133. Though the general structure of bone and teeth is 

 shown moderately well when the tissue has been decalcified (§ 131), 

 the Haversian canals, canaliculi and lacunae of bone and the denti- 

 nal tubules of the teeth are shown much better in sections of dried, 

 non-decalcified tissue, rendered sufficiently thin for microscopic ex- 

 amination by grinding or filing. 



§ 134. Directions for procedure. Prepare thin transverse 

 sections of dried bone in accordance with the directions below. 

 Longitudinal (radial) sections and tangential (surface) sections may 

 also be prepared in the same manner, the former to show the Haver- 

 sian canals and their anasomoses, the latter to indicate the shape of 

 the lacunae as seen in a different plane. 



