EAR AND NOSE. 415 



modification of Golgi's method. The latter staining is per- 

 formed as follows : A piece of retina is dipped into celloidin 

 for a moment, so that a thin layer hardens on the surface. The 

 retina is then placed in the following solution for from twenty- 

 four to forty -eight hours : 3 per cent, potassium bichromate 

 solution, 20 cc. ; 1 per cent, osmic acid, 5-6 cc. The tissue is 

 dried on filter-paper and left in a 0.75 per cent, silver nitrate 

 solution for twenty-four hours. It is then transferred directly 

 to a mixture of 20 cc. of potassium bichromate solution and 

 2-3 cc. of 1 per cent, osmic acid. After from twenty-four to 

 thirty-six hours it is placed again in the 0.75 per cent, silver 

 nitrate solution, where it is allowed to remain for from one to 

 two days. The tissue is now quickly dehydrated and imbedded 

 in celloidin. 



67. Nerves of the cornea can be demonstrated by the gold 

 chloride method. 



15. EAR AND NOSE. 



68. The cochlea is opened at the apex under 0.5 per cent, 

 osmic acid solution and allowed to remain for twelve hours in 

 this solution. After washing the organ in water and hardening 

 it in alcohol, the cochlea is decalcified in 2 per cent, chromic 

 acid or 3 per cent, nitric acid. This takes a week or more, 

 usually. Sections are cut in celloidin and stained in safranin. 



69. Epithelial cells of the olfactory region of the nasal 

 mucous membrane may be isolated by maceration in 33 per 

 cent, alcohol for from two to three hours, and then transferred 

 for ten minutes to 1 per cent, osmic acid. 



70. The olfactory cells may be stained by Golgi's method. 



