122 Journal of Comparative Neurology. 



and the reduction only extends itself gradually to the nerve 

 fibers also. The reaction displays itself to the fullest extent in 

 the nerve fibers almost exclusively in pieces which have lain 

 a long time in bichromate and are very strongly hardened. 

 I recall in this connection the brains which had been kept very 

 nearly a year in bichromate: they showed an almost universal 

 very fine stain of the bundles of nerve fibers and of their finest 

 subdivision. 



' ' Treatment and preservation of mieroscopical preparations. 

 The only special precaution required by preparations made by 

 means of the sublimate reaction before they are mounted in 

 glycerine or balsam is a careful washing in water. Without 

 this precaution a precipitate in the form of a black powder or 

 needle-shaped crystals is formed in the sections some days after 

 mounting and if it does not entirely spoil, yet seriously mars 

 them. As to the rest, the usual mode of preparation is employ- 

 ed : mounting in glycerine, damar or Canada balsam after the 

 necessary dehydration in absolute alcohol and clearing in creo- 

 sote or clove oil. No further precaution is necessary. 



" When I described this method the first time^ I expressed 

 the conviction that it could be still further perfected so as to 

 yifld finer results than those hitherto attained by me. Practice 

 has later led me to some modifications which have improved it. 

 But it has experienced another important development owing to 

 the perservering ex[)criments of Dr. Mondino who succeeded in 

 applying the process with remarkable success to nothing -less 

 than a whole human brain. I will here add the words them- 

 selves in which this observer summarizes the advantages which 

 one can gain from the use of the bichloride of mercury for the 

 study of the central nervous system. 



'Camili.O Goi.cn. I)i una nuova reazione apparenteniente nera delle cel- 

 lule nervose cerebral! ottenuta col bichluro di mercurio. Archivio per le Sc. 

 med.. Vol. III. 



