334 CYTOLOG1CAL METHODS. 



Lemon juice (fresh, filtered) has been warmly recommended as a fixative 

 for nuclei by VAN GEHUCHTEN (Anat. Anzeig., iv, 1889, p. 52). Fix for 

 five minutes, wash well with water and stain with methyl green, and exa- 

 mine in liquid of Ripart and Petit. 



Heat has been recommended, but I believe it to be altogether objection- 

 able. HENKING (Zeit. f. wiss. Zool., xcix, 3, 1890, p. 503 ; Zeit. f. wiss. 

 Mik., vii, 2, 1890, p. 211) has found that it totally destroys achromatic 

 structures. 



638. Chromatin Stains, For fresh or lightly fixed tissues 

 methyl green is the most generally useful nuclear stain. For 

 the properties of this reagent see ante, 109. It may be 

 used either alone, or in the form of Ehrlich-Biondi mixture 

 (see below). 



Bismarck brown is another useful stain for such objects. 

 It may be used in aqueous solution with acetic acid or with 

 hydrate of chloral, or dissolved in dilute glycerin. Alum- 

 carmine may occasionally be useful. Ehrlich's ha3inatoxylin 

 or Mayer's haemalum will render services for osmium objects. 

 Methyl violet, employed according to the method of GRASEK 

 ( 111), may also be found a very useful stain. 



For sections of hardened tissues we have the choice be- 

 tween the finer liaeinatein stains (haemalum, or Ehrlich's or 

 Bohmer's hgematoxylin) and those obtained by means of 

 safranin, gentian violet, Victoriablau, and some other anilins, 

 used according to the indirect or Flemming's method. This 

 has been so fully explained in Chap. VIII that it is only 

 necessary to refer the reader back to the paragraphs in 

 question. Flemming's orange method has been given in 258, 

 and the Ehrlich-Biondi mixture in 259, and will be further 

 considered in the next section. 



BABES'S supersaturated safranin stain (Arch. f. mik. Anat., 

 xxii, 1883, p. 361) may also occasionally be useful. It is us 

 follows : A supersaturated solution of safranin in water is 

 warmed to 60 C. and filtered warm. On cooling, it becomes 

 turbid through the formation of small crystals. Sections tire 

 placed in a watch-glass with some of this turbid solution, and 

 the whole is warmed for a few seconds (till the liquid becomes 

 clear) over a spirit-lamp. Allow the whole to remain for one 

 minute, and wash out with water, and treat with alcohol and 

 turpentine in the usual way. Tissues which do not take on 

 the stain at once must be warmed over and over again. Clove 

 oil must be avoided for clearing. 



