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MANUAL OF HISTOLOGY. 



Preparation of dry bone. In order to study the char- 

 acteristics which have just been described, any human long 

 bone may be taken. It should be stripped of its soft parts, 

 bleached, and well dried. Thin sections are then to be made 

 both in a longitudinal and transverse direction, with a watch- 

 spring saw. 



Next, cleanse them well in water to which a little bicar- 

 bonate of soda has been added ; then place on a whetstone 

 and grind down by rubbing backward and forward with the 



finger until they are suffi- 

 ciently thin ; or the sections 

 may be placed between two 

 plates of ground glass and 

 rubbed down. 



Finally, when so thin that 

 type may be read through 

 them, mount either dry or 

 in Canada balsam or dam- 

 mar varnish. All the char- 

 acteristics already described 

 may then be seen. 



Preparation of decalci- 

 fied bone. Another method 

 consists in first removing the 

 earthy salts. If it is desira- 

 ble to accomplish the work 

 rapidly, cut the bone to be 

 prepared into the smallest 

 available pieces and immerse 

 from four to five days in a 10 

 per cent, watery solution of 



Pro. 36. -Longitudinal section of human ulna, show- hydrochloric acid, 

 ing the Haversian canals forming meshes. (Eollett) mi 



The completion of this 



process may be determined by testing the bone with a fine cam- 

 bric needle. So long as it meets with resistance, the presence 

 of the bone-earths is certain ; on the other hand, if it enter 

 easily, the process of decalcification is over, and the piece ready 

 for cutting. 



Now wash thoroughly in water, so as to remove the acid, 

 place in 80 per cent, alcohol, gradually increasing the strength 

 to 95 per cent. The specimen is then ready for use and may 



