148 The Microscope. 



SOME OBSERVATIONS ON THE DISTRIBUTION AND 

 TERMINATION OF NERVES IN THE HUMAN LUNGS. 



BY EDWIN F. BECKWTTH, M. D., URBANA, OHIO. 



IN the following observations the lungs of several human 

 adults were obtained fresh from the post-mortem table, great 

 care being taken in procuring the lungs of subjects the autop- 

 sis cadaveris of whom had been conducted within a very short 

 time after death. 



Aware of the futility of hoping to obtain good results from 

 any known cause of preparation and staining of the nerves of 

 the lungs, it was found necessary to seek a new method, — and 

 after months of hard work, with many miserable failures, the 

 following, a modification of a process lately promulgated in 

 Germany for staining brain tissues, was found to answer. 

 Harden fresh lung for about ten days in the following solution : 



Bichromate of Potash 2.5% to which is added Sulphate of Copper 

 C. P. to the amount of 0.5%. The tissue is then frozen in microtomes 

 and suitable sections made, which are treated with — 



Gold Chloride 0.5% — 2 to 10 minutes in the dark. 



Washed through distilled water. 



Sodium Hydrate 1 to 5 — until cleared up. 



Potassium Carbonate 10.% — 30 to 60 minutes. 



Dried with absorbent paper. 



Potassium Iodide 10.% — 15 minutes, when gold will be nicely 

 reduced. 



The nerves and ganglia in sections thus prepared are of a 

 deep red or violet color, occasionally shading off into a bluish 

 green, the other tissue being red. The differentiation in color 

 is sharp, so that nerve tissue may be recognized by its color 

 alone whenever seen. 



The above described method of preparation differs very lit- 

 tle from the German process, with the exception of the Potas- 

 sium Carbonate, which I believe essential to success ; as in my 

 hands, the unmodified process failed to give good results, when 

 used on lung tissue. A great advantage of this method consists 

 in the fact that the reduction of gold always takes place in a 

 uniformly even manner ; and with little practice, perfect stain- 

 ing can be accomplished with every section. 



Unfortunately, as in other gold preparations, these speci- 

 mens spoil in a short time unless preserved in the dark in 40% alco- 

 hol, and when examined should be temporarily mounted in 

 glycerine. 



