EMBRYOLOGY 373 



wash in distilled water slightly, diji into 70 per cent, alcohol, and 

 differentiate in 90 per cent, alcohol. 



At this stage the original method recommends downgrading 

 to 50 per cent, alcohol and dipping into 2 per cent, phospho- 

 tungstic acid in water, and then upgrading to absolute, xylol 

 and balsam. This stage may be omitted if it is found to extract 

 the stain too much. Collagen fibres blue, protoplasm clear blue, 

 keratohyalin red, keratin yellow red. This stain is excellent for 

 demonstrating the structure of glands and genital organs. Unna's 

 stain may be used alone, staining for twelve hours. 



813. P. Masson's Iron Haematoxylin, Acid Fuchsin and Anilin 

 Blue {Traite de Pathologie Medicale, Maloine, Paris, 1923). Pre- 

 pare the following solutions : (A) Acid fuchsin, 1 grm., glacial 

 acetic, 1 c.c, distilled water, 200 c.c. (B) Phosphomolybdic acid, 

 1 grm., distilled water, 100 c.c, (C) Anilin blue to saturation in 

 3 per cent, acetic acid in water, 100 c.c. 



The anilin blue solution is prepared by boiling 100 c.c. of 

 distilled water in a flask, adding 2 to 3 grm. of anilin blue, and 

 then taking away the Bunsen. Two or three c.c. of acetic acid 

 are added and the flask is plugged with cotton-wool and allowed 

 to cool, and then the contents filtered. 



Sections are first stained in iron-alum haematoxylin. The 

 subsequent operations will take out some of the stain and the 

 correct degree of under differentiation of the ha?matoxylin must 

 be ascertained experimentally. Rinse in water and transfer to 

 solution A for five minutes ; rinse again and transfer to solution B 

 for five minutes. Take out the slides and without rinsing, drop on 

 5 or 6 drops of solution C. Agitate the slide for a few moments 

 till the blue mixes ; time from two to five minutes to be ascer* 

 tained experimentally. Rinse in aq. dest., place in 1 per cent, 

 acetic acid for five minutes to one half-hour to wash off excess 

 phosphomolybdic. Transfer slides to absolute alcohol with 1 per 

 cent, acetic acid, thirty seconds — then pure absolute alcohol, 

 and Canada balsam to which some salicylic acid has been 

 added. 



Results are chromatin black, cytoplasm and fibres red in 

 various shades, collagen and mucus blue. 



814. H. de Winiwarter's Safranin — Gentian Violet and Orange 

 Triple Stain {Arch, de Biol., xxxiii, 1923). Fixation. Flemming's 

 fluid (twenty-four hours), or some one of the heavier osmicated 

 chrome fixatives. De Winiwarter uses Meves' fluid (§ 47), and 

 often adds urea according to E. Allen's procedure (§ 115). Stain- 

 ing is carried out on sections mounted on slides. The safranin 

 must be a good one, bright and actively staining, without which 

 the whole process will fail. 



If the tissue has not been fixed in osmic fixatives, or has soaked 

 for a long time in alcohol, the faculty for taking the triple stain 



