42 PRACTICAL HISTOLOGY [V 



up to 75 p.c., place it for one minute in the rubin mixture. Trans- 

 fer it to 95 p.c. alcohol, and treat in the usual way. If required, a 

 little more picric tint may be given by treating it as in 7, after 

 it has been stained with the rubin mixture. Acid magenta 

 stains especially the connective tissue, and is best used when a 

 small amount only of this tissue is present (cp. App. p. 310). 



11. Ehrlich-Biondi stain. This is a mixture of methyl- 

 green 00, orange G, and rubin S (acid magenta), (cp. p. 310). 

 The methyl-green stains nuclei, orange G stains haemoglobin, 

 rubin S stains connective tissue ; cell-substance is stained chiefly 

 by the rubin, slightly by the orange G. Sections are placed in it 

 from hour to a day ; as a rule they must be passed rapidly 

 through alcohols in order to preserve the nuclear stain. Xylol 

 or cedar- wood oil should be used as the clearing agent. 



The solution on keeping often loses its red tint, and gives 

 little else than the nuclear stain; the colour may be brought 

 back by adding a little dilute acetic acid, but if excess is added 

 the rubin S only will stain. The student will probably obtain 

 better results with the double stains given above than with this. 



For iron-hsematoxylin stain see p. 287. 



