SO PRACTICAL HISTOLOGY. 



i per cent, solution of chloride of gold and cadmium (30-60 minutes) 

 in the dark. Wash ; then in i per cent, formic acid (24 hours) 

 in the dark, and then for 12 hours in sunlight. Finally for 24 hours 

 in pure formic acid. Wash. Tease and mount in glycerine. 



F. Double, Treble, or Multiple Stainings. 



It is possible to stain a section so that the several parts of it may 

 be differently stained. This may be done either by staining succes- 

 sively with different stains, or by mixing the dyes in one fluid, and 

 staining the section with the mixture, whereby one part takes up 

 one of the dyes and another part one of the other dyes. Thus one 

 gets an elective and differential stain. It is possible thus to combine 

 a nuclear stain with one which stains only the protoplasm of the 

 cells, such as eosin or orange. 



Amongst double stains are the following : 



1. Picro-carmine (p. 66), one of the most valuable we possess, 

 and which we owe to Ranvier ; and Picro-litho-carmine. If the 

 section is to be mounted in glycerine or Farrant's solution, do not 

 wash it 'in water. If it is to be mounted in balsam, the alcohol in 

 which it is washed should contain picric acid the same result is 

 obtained by using clove-oil with picric acid dissolved in it other- 

 wise only a carmine stain is obtained. 



2. Carmine and Aniline Blue. Stain a section in borax-carmine, 

 and then in very dilute aniline blue, specially useful for the glands 

 of the fundus of the stomach. In other tissues the nuclei are red 

 and the perinuclear parts blue. 



3. Hsematoxylin and Eosin. Hsematoxylin is a nuclear stain, 

 the sections are first stained in it, and then in eosin, which stains 

 the general protoplasm of the cell. (See also p. 72.) 



4. Aniline-blue and Safranin (Garbini).-The section is trans- 

 ferred from water. 



Manipulation. 



Aniline-blue sol. (.5 per cent.), 2-4 minutes. 



Wash in water. 



Lithium carbonate (.5 per cent.), a few minutes. 



Hydrochloric acid (.5 per cent.), a transparent blue colour 



is produced. 

 Wash in water. 



Safranin (i per cent.), 10 minutes. 

 Dehydrate in methylic alcohol. 



Clarify in oil of cloves (2 parts) and cedar-oil (i part). 

 Xylol-balsam. 



This is especially useful for some of the salivary glands thus in 

 the sub-maxillary one set of cells is red, the other blue ; in the 

 stomach the parietal cells are red and the inner blue ; the epithelial 



