4 H. HAYS BULLARD 



Nile blue : Teased preparations or frozen sections of fresh tissue 

 or material used after a fixation of two to twelve hours in 20 per 

 cent formalin, are stained fifteen minutes to two hours in a satu- 

 rated aqueous solution of Nile blue chlorhydrate, washed in dis- 

 tilled water five minutes or more, and transferred to tap water. 

 After five minutes in tap water the preparation should assume a 

 reddish hue. If this does not occur a slight amount of alkali 

 may be added to the water. The preparations are mounted in 

 either levulose, potassium acetate, or glycerine. Wlien Nile 

 blue sulphate. is used it is necessary to add a somewhat greater 

 amount of alkali, to the tap water. Fat droplets are stained red; 

 purple or blue, true interstitial granules are stained blue. 



Cresylviolett : Fresh material, or material after two to twelve 

 houis fixation in formalin, is stained in a dilute aqueous solution of 

 Cresylviolett or Cresylechtviolett for ten to twenty minutes, then 

 washed three to five minutes in distilled water and mounted in 

 levulose syrup. Fat droplets are colorless, or (rarely) a faint red 

 or blue, true interstitial granules are blue. 



For the details of the complicated methods of Weigert, Altmann, 

 Benda and Regaud, the reader is referred to Encyklopadie der 

 Mikroskopischen Technik, Berhn, Wien, 1903, and to the discus- 

 sion of Faure-Fremiet, Mayer and Schaeffer ('10). Benda's 

 method in particular is unnecessarily complex, requiring about 

 two weeks to prepare a specimen, and its results are not uniform. 

 Satisfactory preparations were obtained by a modified Weigert 

 method which may be briefly stated as follows : 



Fix twenty-four hours or more in a 10 to 20 per cent solution of 

 formalin (4 to 8 per cent formaldehyde) with the addition of 0.75 

 per cent sodium chloride, then mordant in 5 per cent aqueous 

 potassium bichromate four to seven days. Imbed in paraffin 

 and section. Stain warm two to six hours in a mixture contain- 

 ing hematoxylin 1 gram and 2 per cent acetic acid 200 cc. Decol- 

 orize by use of Weigert's differentiating fluid, or by dilute (0.12 

 per cent) potassium permanganate followed by the oxalic acid- 

 potassium sulphite mixture of the Pal- Weigert technique. Dehy- 

 drate, clear, and mount in balsam. Or prepare paraffin sections, 

 as above, stain in Altmann's acid fuchsin, decolorize in picric 



