32 MICROSCOPY. 



Especially valuable for delicate tissue. Time, two to twenty-four 

 hours ; dehydrate with alcohol. 



HARDENING REAGENTS. 



Muller's fluid, corrosive sublimate solution, chromic acid, and 

 others of the reagents named above may be used for hardening pur- 

 poses. For general use, alcohol will be found invaluable. The tis- 

 sue should be passed through increasing strengths of alcohol, seven- 

 ty per cent, eighty per cent, ninety per cent, ninety-five per cent, 

 and absolute. It should be allowed to remain twenty-four hours in 

 each, except that one to six hours will suffice for absolute alcohol. 

 Ethyl alcohol should be used, or, in lieu of this, methyl alcohol makes 

 a good substitute. To prepare absolute alcohol, dehydrated copper 

 sulphate may be added to the ethyl or methyl alcohol. This will ab- 

 sorb the water present. 



EMBEDDING MEDIA. 



Paraffin and celloidin are extensively used for embedding tissue. 

 The process for each has been fully explained in the chapter on 

 " Microscopic Technique." 



FIXATIVES. 



Collodion and clove oil mixture. Mix one part of collodion with 

 three parts of clove-oil. 



Egg-albumen and glycerine. Filter the whites of several eggs 

 and add to the filtrate an equal volume of glycerine. To the mix- 

 ture add a few drops of carbolic acid or a small piece of thymol to 

 prevent putrefaction. 



PARAFFIN SOLVENTS. 



Xylol, turpentine, chloroform, and benzole are commonly used 

 to remove paraffin from sections. A good plan is to immerse the 

 slide containing the section for a few moments in xylol, and then 

 transfer to turpentine for ten minutes. 



STAINING SOLUTIONS. 



The following staining preparations are those most frequently 

 used, and will be found adequate to the work required by this text. 

 Should others be needed, the formulae can be obtained from more 

 advanced works. 



