SPFXL\L STAINING METHODS 29 



In using this stain add to each cubic centimeter required of the 

 above solution i drop of a 7-per-cent. solution of ferric chlorid in 

 absolute alcohol. 



Sections are carried from alcohol into the staining fluid where they 

 remain one to three hours. The stain should be kept covered to 

 prevent evaporation. Sections are next washed in water one or two 

 minutes and examined under the microscope. If further differentia- 

 tion is desirable, place a few seconds in i-per-cent. aqueous solution 

 ferric chlorid. Wash in water. Counterstain in 0.2-per-cent. 

 eosin, dehydrate in alcohol, clear and mount in balsam. 



Elastic tissue is stained black, nuclei take hajmatoxylin, while 

 other connective tissues, myelin and neuroglia stain with eosin. 

 Fixation by Zenker's fluid gives perhaps the best results although 

 the stain may be used after other fixations. Water in the staining 

 fluid causes precipitates. It is therefore important to see that all 

 dishes used are perfectly dry or washed with alcohol before using. 

 Too much ferric chlorid gives precipitates and overstaining, too 

 little results in failure of the elastic fibres to stain. 



(5) GoLGi's Chrome-silver Method for Demonstrating Se- 

 cretory Tubules. — Small pieces of perfectly fresh tissue, e.g., Hver, 

 are placed in the following: 



Potassium bichromate, 4-pcr-cent. aqueous solution, 4 vols. 

 Osmic acid, i-per-cent. aqueous solution, i vol. 



After three days they are transferred without washing to a 0.75-per- 

 <;ent. aqueous solution of silver nitrate, which should be changed as 

 soon as a precipitate forms. The specimens remain in the second 

 silver solution from two to three days, after which they are rapidly 

 dehydrated, embedded in celloidin, and cut into rather thick sections. 



(6) Mallory's Phosphomolybdic Acid Hematoxylin Stain for 

 Connective Tissue. — Thin sections are placed for from two to ten 

 minutes in a lo-per-cent. aqueous solution of phosphomolybdic acid. 

 They are then washed in distilled water and transferred to : 



Phosphomolj'bdic acid, lo-per-cent. aqueous solution, 100. o c.c. 

 Distilled water, 200.0 c.c. 



Haematoxylin crystals, i • 75 gm- 



Carbolic-acid crystals, 5 . 00 gm. 



The phosphomolybdic acid and water are first mixed, after which 

 the haematoxylin and carbolic acid are added. 



After staining from ten to twenty minutes the sections are washed 



