76 DIRECT NDCLEAE STAINS. 



The colour is not very easily soluble in water. You may: 

 boil it in water, and filter after a day or two (WEIGERT, in 

 Arch. f. mile. Anat , xv, 1878, p. 258). You may add a little 

 acetic or osmic acid to the solution. MAYSEL (ibid., xviii,. 

 1880, pp. 237, 250) dissolves the colour in acetic acid (this 

 solution does not give a permanent stain). Alcoholic solutions 

 may also be used. Paul Mayer recommends a saturated solu- 

 tion in 70 per cent, alcohol ; or CALBERLA'S glycerin-and- 

 alcohol mixture, or dilute glycerine (say of 40 per cent, to 50 

 per cent.) may very advantageously be employed. 



The watery solutions must be frequently filtered. The 

 addition to them of carbolic acid has lately been recommended, 

 vide Journ. Roy. Hie. Soc., 1886, p. 908. Bismarck brown 

 stains rapidly, but never overstains. The stain is permanent 

 both in balsam and in glycerin. 



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

 but it may also be employed for staining sections by the de- 

 coloration method (see above, 107). 



As has been noted above ( 93), Bismarck brown has the 

 property of staining certain cellular elements during life (for 

 this purpose it is necessary to see that the colour employed 

 be pure and neutral) . 



111. Methyl Violet (Methylanilin = anilin-violet = Paris violet = in- 

 chiostro di Leonardi). The following process has been recommended by 

 OETH (Amer. Mon. Micr. Journ., i, 1880, p. 143 ; Journ. Roy. Mic. Soc., 

 N.S., i, 1881, p. 137) : Sections are to be soaked in water, and then brought 

 into the following solution : 



Anilin violet 1 part. 



Acetic acid 300 parts. 



Mount, without washing out, but simply draining, in acetate of potash 

 (acetate 2 parts, water 1 part). 

 . The stain will probably fade within a year or two. 



This process does not appear to be of more than very limited applicability. 

 The following, however, due to GEASER (Deutsche Zeit.f. Chirurgie, xxvii, 

 1888, pp. 538584 ; Zeit. f. wiss. Mik., v, 3, 1888, p. 378) may, be very 

 generally useful. 



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). Schiefferdecker, whose 

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



