X Journal of Comparative Neurology. 



We have already given an epitome of the results of Golgi and Kol- 

 liker i and refer the reader to the list of papers beyond. A very conven- . 

 ient summary is given by A. Van Gehuchten in the work referred to above, 

 while his own results are elaborated particularly in La structure des 

 centres nerveux la moelle epiniere et le cervelet, La Cellule, VII, i. 

 1891. 



The shorter method introduced by Golgi and generally followed con- 

 sists in the precipitation of chromate of silver in the tissue in accordance 

 with the varying susceptibility of the parts. It will be self-evident that 

 embryonic or at least young specimens will possess an advantage in the 

 latter respect over older and less permeable tissues. The procedure is 

 as follows: Small specimens of the tissue, 3-6 mm., are placed in 2 per 

 cent, bichromate of potash for 4-5 days and then for 24-30 hours in a 

 mixture of 2 parts one per cent, osmic acid and 8 parts 2 per cent, bichro- 

 mate, and finally in 0.75 per cent, nitrate of silver solution. Acording to 

 Dr. Sala, Golgi's assistant in Turin, the various modifications since intro- 

 duced offer slight or no advantage over this simple process. Van Gehuch- 

 ten, on the other hand, claims that the addition of a small amount of 

 formic acid (one drop to 100 cc. of the silver solution) favors a proper re- 

 duction. In this solution the specimen remains several weeks without 

 injury, provided there is sufficient fluid and it be kept in the dark. 



Although Sala regards the cutting of fine sections with the microtome 

 and the paraffin imbedding process described by Sehrwald as an entirely 

 useless refinement, he nevertheless indicates a method of attaching the 

 specimen to a cork with gum arable and sectioning with the microtome 

 under alcohol. Van Gehuchten passes the specimen from silver to 96 per 

 cent, alcohol for 20 minutes, then into absolute alcohol for 15 minutes, 

 after which they remain in dilute solution of celloidin, which is hardened 

 in 70 per cent, alcohol. From the latter in an hour or so they may be re- 

 moved to the microtome. The sections are placed for an hour in silver 

 nitrate solution, thence they pass into 96 per cent, alcohol, then into 

 creosote, are cleared in turpentine and mounted in dammar in benzole. It 

 is recommended to hasten the evaporation of the benzole by placing in a 

 drying oven. 



Fusari obtained his beautiful results by the use of Miiller's fluid fol- 

 lowed by a mixture of that fluid with osmic acid in varying proportions 



\. Journ. Comp. Neurol, March, p. i-ii., p. 95-99 ; June, p. 197-199; also in the 

 Bulletin of I)enison Univ. Vol. V. 



