SECTION ONE 



6. Wash with two changes of 90% alcohol. 



7. Wash with 70% alcohol. 



8. Wash with two changes of distilled water if an aqueous stain 

 is to be used ; but if an alcoholic stain will be used staining may 

 commence immediately after washing with 70% alcohol. 



9. Proceed to stain in accordance with the staining technique it 

 is desired to employ. 



Note: If the section appears opalescent when the xylol or when 

 the absolute or the 90% alcohol is added the presence of water is 

 indicated and it is necessary to retrace each step until the prepar- 

 ation no longer appears opalescent when taken down to alcohol. 



PARAFFIN WAX - PYRIDIN TECHNIQUE 

 A rapid method of dehydrating and clearing 



1. Material is fixed and washed by the standard method. 



2. If a fixative containing mercury has been used, remove mer- 

 curial precipitate by the standard technique. 



3. Immerse the tissue in two changes of Pyridin for two to 

 eight hours in each, according to the nature and thickness of the 

 tissue. 



4. Transfer to a mixture of equal parts of molten paraffin wax 

 and Pyridin in the embedding oven for one half to sixteen hours, 

 depending upon the size and nature of the object. 



5. Transfer to pure paraffin wax in the oven for a quarter to 

 eight hours, depending upon the thickness and nature of the 

 material. 



6. Cast into block and cut sections in the usual manner. 



WATER WAX 

 (Michrome) 



A very rapid and simple method of embedding tissues, obviating 

 the use of dehydrating and clearing agents. 



Water wax is an amorphous water-soluble wax which sets at 

 56° C. to form translucent blocks similar in appearance to paraffin 

 wax but with the complete absence of any trace of crystallization. 

 Fresh or fixed material may be used. 



33 



