664 TECHNIQUE 



This method is only applicable to tissue which has been fixed in 

 95 per cent., or in absolute alcohol. Thionin may be substituted 

 for the methylen blue in the stain. 



1. Warm the stain till steam begins to rise ; then immerse the 

 sections for four to six minutes. They acquire a deep blue color. 



2. Rinse in distilled water. 



3. Differentiate in the anilin alcohol till the sections become a 

 light blue, carefully observing each section (twenty to sixty sec- 

 onds). 



4. Wash in 95 per cent, alcohol. 



5. Clear in equal parts of origanum and cajuput oils, and mount 

 in neutral balsam or in colophonium dissolved in xylol. 



Eosinate of Methylen Blue (Hast ing's Method): 

 .For the somewhat complicated method of preparing the stain 

 the reader is referred to the original article, Johns Hop. Hosp. 

 Bull., 1904, vol. xv, p. 122. The stain is applicable to smears of 

 blood, marrow, splenic cells, etc. When used with smears which 

 contain traces of fat, a preparatory treatment with a 2 per cent, 

 aqueous solution of sodium metaphosphate, which probably serves 

 as a mordant, improves the staining properties. Otherwise the 

 stain is applied without previous fixation. 



1. Stain for one minute. 



2. Dilute the stain with several volumes of distilled water, and 

 continue the stain for five minutes, or until satisfactorily differen- 

 tiated. 



3. Wash with distilled water. 



4. Dry and mount. 



Golgi's Stain for Nerve Cells: 



I. Mordant: 



1 per cent, aqueous solution of osmium tet- 



roxid 10 cc. 



3 per cent, aqueous solution of potassium bi- 

 chromate 40 cc. 



II. Silver Solution : 



Silver nitrate (crystals) 0.75 grm. 



Distilled water 100 cc. 



This method is only applicable to fresh tissues, and the best 

 results are obtained when the tissue is taken from a fetus or from 

 an animal not over three days old. Thin slices or small bits of tissue 

 must be used. 



1. Fix in the mordant for ten days, frequently changing the 



