HJSTOLOGIC TECHNIQUE. 21 



dyes, for instance, such as hsematoxylin, carmine, methylene- 

 blue, constitute a class of stains very much used, which 

 impart to the cell-nuclei a deep color, while they leave the 

 bodies of the cells uncolored ; the general stains, as eosin, on 

 the contrary, stain the cell-protoplasm, but not the nuclei. 

 There are numerous other processes to be carried out ; but the 

 limits of this work do not permit the consideration of practi- 

 cal methods, for which reference may be made to the numer- 

 ous special works on that subject. 



