446 MYELIN STAINS. 



For Sheldon's modification, which is also based on a formalin fixation, 

 see Folia, Neurobiol, viii, 1914, p. 1. 



Modifications of Weigert's Method. 



857. PAL'S Method (Wien. med. Jahrb., N.F. i, 1886, p. 619; 

 Ztschr. wiss. Mikr., iv, 1887, p. 92 ; Med. Jahrb., N.F. ii, 1887, 

 p. 589). One proceeds as in WEIGERT'S process, but omitting the 

 copper bath. 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 

 potassium permanganate, rinsed in water, and brought into a 

 decolorising solution composed of : 



Oxalic acid . . . . . . 1-0 grm. 



Potassium sulphite (S0 3 K 2 ) . . . 1-0 

 Dist. water 200-0 c.c. 



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

 the white matter remaining blue. If the differentiation is not 

 complete the whole process can be repeated a second time, and so on. 

 The sections should now be well washed out, and may be counter- 

 stained with Magdala red or eosin, or (better) with picrocarmine or 

 acetic acid carmine. 



Pal's process gives brilliant results, the ground of the preparations 

 being totally colourless. WEIGERT (Ergebn. Anat., vi, 1896, p. 21) 

 considered it superior to his own for thick sections, but not so safe 

 for very fine fibres. 



MARCUS stains by the Pal method sections of material hardened in 

 formalin. 



GUDDEN (N enrol. Centrbl., xvi, 1897, p. 24) makes celloidin sections of 

 material hardened in 5 to 10 per cent, formol followed by alcohol, treats 

 them for ten hours with 0-55 per cent, chromic acid, rinses with water, 

 and treats with 80 per cent, alcohol ; then stains by the method of Pal, 

 adding to the hsematoxylin a few drops of dilute nitric acid (MINNICH). 



TSCHERNYSCHEW and KARUSIN (Ztschr. wiss. Mikr., xiii, 1896, p. 354) 

 stain for twenty-four hours in KULTSCHITZKT'S haematoxylin. 



PAVLOW (ibid., xxi, 1904, p. 14) uses the permanganate twice as 

 strong as Pal. 



KOZOWSKY (N enrol. Centrbl., xxiii, 1904, p. 1041) stains as Weigert, 

 and differentiates the sections first with 1 per cent, permanganate, till 

 the grey matter comes out brown, and finishes the differentiation 

 with Liq. ferri sesquichlorati. 



POTTER (Ztschr. wiss. Mikr., xxvii, 1910, p. 238) stains as Weigert, 

 last , and differentiates first in 0-25 per cent, permanganate, then in 

 borax ferricyanide. 



