1-564 Journal of Applied Microscopy 



Rinse away the excess stain for a few minutes with distilled water. Then 

 transfer the sections to the decolorizer : 



Distilled water ----- 1000.0 c. c. 



Potassium ferricyanide - - - 12.5 grams. 



Borax ------- 10.0 " 



The decolorizing must be watched carefully so that it may be stopped at just the 

 right moment. The gray matter should be bleached to a yellow tint, while the 

 medullated nerve-fibres should remain a bright blue-black. When the action has 

 gone far enough, transfer the sections to clean tap-water, running, if possible, in 

 which they must be washed for some time. If the washing be thorough, the 

 stain will not fade. 



Dehydrate, clear, and mount the sections in the usual manner. 



6. Staifihig Isolated Nerve-Cells. 



Some plan for making preparations of entire nerve-cells is altogether desirable 

 for class demonstrations. For this purpose, the writer is about to risk his repu- 

 tation as a modern microscopist by advocating the use of a stain which the older 

 workers are supposed to have forgotten, and of which the younger ones have 

 never even heard. This stain is Beale's Carmine. No other method known to 

 the writer is capable of yielding preparations of nerve-cells rivaling in clearness 

 and beauty the results of the procedure here indicated. 



Secure the cooperation of a butcher, and have him furnish the lumbar cord 

 of the ox in a perfectly fresh condition. Slit the cord lengthwise so as to expose 

 the gray matter. Scoop out quite small pieces from the anterior cornua. Place 

 these fragments directly in the following stain : 



Carmine --..-. 3 grams. 



Ammonia - - - - - - 10 c. c. 



Glycerine - - - - ' - - 300 c. c. 



Water - - - - - - - 300 c. c. 



Alcohol - - - - - - 75 c. c. 



(Dissolve the carmine in the ammonia with the aid of gentle heat ; allow the solu- 

 tion to stand in an open dish for an hour ; then add to the other ingredients. 

 Filter.) 



The pieces of nervous matter are to lie in this stain for several weeks. Then 

 transfer them to dilute glycerine acidulated with a trace of acetic acid. After a 

 few days, replace this medium with pure glycerine. 



Place a bit of the stained tissue on a slide, in a drop of glycerine. Press a 

 cover-slip straight downward on the mass so as to spread the nervous matter in 

 an even film. Avoid rotating the cover-slip. Some of the preparations will 

 necessarily show so few cells as to be practically valueless, but others will be 

 crowded with brilliantly stained nerve-cells in all their completeness. Aside 

 from the value of such a preparation for purposes of demonstration, it is worth 

 noting that the fibrillar elements of the neurone are made particularly evident. 



7. Peripheral Neri'e-Fibres. 



Place short lengths of the sciatic nerve of the frog in five-tenths per cent, 

 osmic acid for about twenty-four hours. Keep in the dark. The osmic acid 



