GOLGI'S METHODS FOR MEDULLATED NEKVES. 311 



minutes in 0*05 per cent, aqueous solution of chromic aci<V 

 rinsed in water, dehydrated, cleared, and mounted in balsam. 

 This method is stated to be peculiarly adapted for the 

 demonstration of very fine fibres and their relations to 

 ganglion-cells. 



HAMILTON (Journ. of Anat. and Physiol, xxi, 1887, p. 444 ; Journ. 

 Roy. Mic. Soc., 1888, p. 1051) mordants his preparations with a copper sul- 

 phate solution, and makes sections by the freezing method, after imbedding 

 in collodion. 



BEEVEE (Brain, 1885, p. 227; Journ. Roy. Mic. Soc., 1886, p. 898) 

 gives a very slight modification of Weigert's original process. 



PAL (Wien. med. Jahrb., 1886 ; Zeit. f. wiss. Mik., iv, 1, 1887, p. 92; 



Med. Jahrb., 1887, p. 589 ; Zeit. /. wiss. Mik., 1888, p. 88) describes the 



following process : After staining in the hsematoxylin solution the sections 



are washed in water (if they are not stained of a deep blue, a trace of lithium 



carbonate must be added to the water). They are then brought for twenty 



to thirty seconds into 0'25 per cent, solution of permanganate of potash, 



rinsed in water, and brought into a decolouring solution composed of 



Acid. Oxalic, pur. . . . 1*0 



Kaliuin Sulfurosum (S0 3 K 2 ) . . TO 



Aq. dest. . . . 200'0 



In a few seconds the grey substance of the sections is decolourised, the 

 white matter remaining blue. The sections should now be well washed out, 

 and may be double-stained with Magdala red or eosin, or (better) with picro- 

 carmine or acetic-acid-carmine. 



For further details as to the somewhat elaborate minutiae of the process 

 see the papers quoted, or BEHEENS, KOSSEL, and SCHIEFFEEDECKEE'S, Das 

 Mikroskop, i, p. 199. 



652. GOLGI'S Methods for MeduUated Nerves. (1) Bichromate 

 and Silver-nitrate Process. I take the following resume of this 

 method from the interesting paper of Grolgi's pupil, REZZONICO, 

 " Sulla struttura delle fibre nervose del midollo spinale," in 

 the Archivio per le scienze mediche, iv, No. 4 (1879), p. 85. 



1. Take pieces of perfectly fresh spinal cord, and soak 

 them in a 2 per cent, solution of bichromate of potash, for a 

 period of time varying according to temperature. (In summer 

 eight to fifteen days may suffice, in winter about a month is 

 necessary.) 



2. Wash them, and put them into a 0*75 per cent, solution 

 of nitrate of silver. The period of immersion therein depends 

 on the temperature : in summer the reaction will be complete 

 throughout the tissues in two or three days ; in winter eight, 

 ten, or more days. 



