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Ipreparing Sections of ^eetb for IbistoloQi? 



an£) Bacteriology. 



PART II.-HISTOLOGY PRACTICAL. 



By Prof. V. A. Latham, D.D.S., F.R.M.S., etc. 



Sectio?i II.— SOFTENED SECTIONS. 



FOR this purpose several reagents may be used, but all seem 

 to act by the removing of the calcareous matter and the 

 hardening of the soft tissues of the teeth. It is most 

 important that the last should be thoroughly well attended to, or 

 else we do not get a correct idea of the character and structural 

 size of the elements found in the tooth. Chromic acid is the 

 first ; a one-sixth per cent, up to one-half may be used. The 

 former is preferable, and is made by adding one gramme to 600 cc. 

 of distilled water, or 15 grains to the pint, a quantity of which 

 should be kept on hand in order to immerse a freshly extracted 

 tooth that may be desired for examination. 



Tie a piece of cotton round a fresh tooth, and suspend it in 

 the fluid (one part of spirit to two parts aci,d), carefully stirred so 

 as to be covered by a quantity of the solution. Where the crown 

 of the tooth is not required for examination, it is better to saw it 

 off at the neck so as to allow the stains and reagents to penetrate 

 the tissues. The hardening fluid must be changed the second day 

 and on the fifth and eighth days. On the ninth day it is placed 

 in a mixture consisting of two parts of spirit and one of water well 

 stirred ; and on the tenth day into pure spirit and left till desired 

 to use. If desired to soften at the end of the eighth day, a few 

 drops of hydrochloric acid can be added to decalcify, which may 

 be tested by passing a fine needle through the tooth ; then wash 

 well to remove the acid ; then place for a day into two parts spirit 

 and one water, and the next day into ordinary spirit; on the 

 fourth day embed and cut. 



To Embed in Parafl&n.— A small tin or paper mould should 

 be made and some melted paraflin poured into it. The tooth 

 is then quickly dipped in and withdrawn till quite cool. As the 

 paraffin is now cooling, place the tooth in it near the hand of the 



