312 CYTOLOGICAL METHODS. 



variety of mixtures such as Carnoy, Bouin and Zenker with or 

 without acetic acid, etc. Staining in Ehrlich-Biondi, Ehrlich's 

 haematoxylin and azoeosin or Biebrich scarlet (by Scott's method, 

 described below), by Pappenheim's pyronin and methyl green, by 

 Auerbach's fuchsin and methyl green, Zimmermann's fuchsin iodine 

 green, and by Mann's methyl-blue eosin. The double and triple 

 simultaneous stains are valuable. 



Auerbach's stain consists of equal parts of 1 per cent, methyl 

 green, and 1 per cent, acid fuchsin ; Pappenheim's stain ( 292) 

 consists of methyl green and pyronin, a red basic stain instead of 

 the acid fuchsin of the Auerbach. Another stain which is very 

 valuable is the triple stain of Ehrlich, but it is less easy to work than 

 Auerbach or Pappenheim. In all work on nuclei and nucleoli, 

 Mann's methyl-blue eosin will be found especially helpful, because 

 the eosin-staining from this mixture is generally more restricted 

 and intense than when one stains in some basic dye followed by 

 eosin, or vice versa. Very beautiful results are occasionally procured 

 by using Unna's polychrome methylene blue ( 337). 



Recourse should be made to the methods for the mitochondria, 

 particularly those such as Champy-Kull and Bensley-Cowdry 

 (compare with Auerbach preparations), for many nucleoli are 

 compound bodies almost certainly containing lipoids or fats. 



The formalin silver nitrate techniques of Cajal or Da Fano should 

 be tried, and wherever possible tests on fresh cells should be carried out 

 (e.g. digestion, methyl green, etc., etc.). 



It seems indicated that further observations carried out on 

 nucleoli of live cells in tissue cultures will provide new facts, 

 especially with regard to the part played by these bodies during 

 mitosis. See sections on " Tissue Culture." 



669. S. Gr. SCOTT'S Standard Hsematoxylin and Biebrich Scarlet for 

 Chromophility (Jour. Path, and Bact., xvi, 1912). Fix tissue in 

 sublimate formalin, Zenker without acetic, Helly's Zenker-formalin, 

 Miiller, or formalin. All strongly acid fixatives must be avoided, 

 for the Ehrlich's haematoxylin will not then stain anything but 

 nuclei, and these only faintly. Paraffin sections are made and fixed 

 ,to slide. After removal of paraffin with xylol, and this with alcohol, 

 sections of material fixed in sublimate solutions are treated with 

 iodine for three or four minutes (0-2 per cent, iodine in 80 per cent, 

 alcohol). Rinse off excess iodine with a little alcohol and remove 

 all iodine from tissue with a 0-25 per cent, solution of Na 2 S 2 3 in 

 50 per cent, alcohol, not in water as recommended by HEIDENHAUN 

 (Arch.f. d. ges. Pkys., Bonn, 1902, Bd. xc, 115). This is a most 



