COAL-TAK CHROMATIN STAINS. 211 



tions may also be used, e. g. saturated aqueous solution 

 diluted* with one third volume of 90 per -cent, alcohol; or 

 CALBERLA'S glycerin-aiid-alcohol mixture, or dilute glycerin 

 . (say of 40 per cent, to 50 per cent.) may very advan- 

 tageously be employed. 



The watery solutions must be frequently filtered. The 

 addition to them of carbolic 'acid has been recommended 

 (vide Journ. Roy. Hie. 8oc., 1886, p. 908). MAYER, however 

 (Mitth. Zool. Stat. Neapel, xii, 1896, p. 315), points out that 

 frequent filtering has the disadvantage that the paper 

 absorbs a great deal of the colour. Bismarck brown stains 

 rapidly, but never overstains. The stain is permanent both 

 in balsam and in glycerin. 



The chief use of this eolour is for staining objects in toto; 

 but it may be employed for staining sections by the regres- 

 sive method ( 275), and also for intra-vitam staining ( 201) 

 (for this purpose it is necessary to see that the colour 

 -employed be pure and neutral). 9 



279. Methyl Violet (Methylanilin Violet, Anilin Violet, Paris 



Violet). GEASER (Deutsche Zeit.f. Chirurgie,xxv\\, 1888, pp. 538 584; 

 Zeit.f. wiss. Mik., v, 3, 1888, p. 378) recommends the following process j 



Sections are stained for from twelve to twenty-four hours in a (presum- 

 ably aqueous) solution so dilute that at the end of that time the sections 

 will have taken up all the colour from the liquid. They are then washed 

 out for a short time in acidulated alcohol, and then in pure alcohol (followed 

 presumably by clearing and mounting in balsam). SCHIEFFEBDECKEB, whose 

 account is here quoted, says that the results, as regards nuclear figures, are 

 even finer than with safrafiin. The method is applicable to objects fixed in 

 " Flemming." 



A useful stain for fresh tissues is also obtained by using dilute acetic acid 

 in the manner recommended above (by EHBLICH) for Dahlia ( 275). 



