STAINING, PRACTICAL AND THEORETICAL 



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 

 A rapid method of dehydrating and embedding 



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. 



WATERWAX D23 

 (Edward Gurr) 



A very rapid and simple method of embedding tissues, obviating 

 the use of dehydrating and clearing agents. 



Waterwax D23 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. 



Technique: 



I . Shake off excess water before immersing the pieces of tissue 

 directly into a bath of waterwax in the embedding oven at 

 55-6° C. and leave for an hour. 



502 



