SECTION TWO 



3. Immerse for at least ten days in 1% aqueous potass, hydrox- 

 ide until the bones are clearly visible through the soft tissue. 



Note: Formalin-fixed specimens require four to six weeks in 

 1% potass, hydroxide. Should the tissue become too soft it may 

 be hardened by immersing for twelve to twenty-four hours in a 

 mixture consisting of equal volumes of glycerin, water and 95% 

 alcohol before returning to the clearing solution. Potass, hydroxide 

 0*5% may be used during the last few days of the clearing. 



4. Wash twenty-four hours in running tap water. 



5. Stain one half to six hours, according to the size of the speci- 

 men, in Solution A. 



6. Wash for thirty minutes in running tap water. 



7. Decolorize seven to fourteen days in Solution B. 



8. Mount in a glass frame and dehydrate by passing slowly 

 through alcohol-glycerin-water mixtures beginning with the pro- 

 portions 1:2:7 and then in succession 2 : 2 : 6, 3 : 3 : 4, 4 : 4 : 2 ; 

 and finally equal parts of alcohol and glycerin only. 



9. Seal in the usual glycerin-alcohol mixture. 



For nervous tissues (Benda's method) 



Solutions required: 



A. Nitric acid, cone. . . . . i volume 

 Distilled water . . . . . . 10 volumes 



B. Potass, dichromate 2% 



C. Chromic acid 1% 



D. Iron alum 4% 



E. Alizarin Red, S, saturated in abso- 



lute alcohol . . . . . . I ml. 



Distilled water . . . . . . 90 ml. 



F. Toluidine Blue o-i% aqueous 



Technique: 



I. Material is fixed in 90-95% alcohol for at least two days. 



57 



