366 NERVES. 



in the haematoxylin solution the sections are washed in water 

 (if they are not stained of a deep blue, a trace of lithium car- 

 bonate 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. . . TO 



Potassium Sulphite (Kalium Sul- 



furosum [S0 3 K 2 ] ) . . 1-0 



Aq. dest. . . . 20OO 



In a few seconds the grey substance of the sections is de- 

 colourised, 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 BEHRENS, KOSSEL, and 

 SCHIEFFERDECKER'S Das Mikroskop, i, p. 199. 



BEEVOR (Journ. Roy. Mic. Soc., 1892, p. 898) says of this 

 process that it is more difficult to carry out than Weigert's, 

 and that it does not show the different forms of fibres so well, 

 but is useful on account of the double stain. 



693. The process of PAL has been modified by SCHAFER (I 

 quote from BEEVOR, 1. c., not knowing where the method was 

 first published) as follows : " The material is hardened from 

 four to six weeks, and after cutting the sections are put into 

 MARCHI'S fluid (1 part of a 1 per cent, solution of osmic acid, 

 and 2 parts of a 3 per cent, solution of potassium bichromate) . 

 Then wash quickly in water and stain with the haematoxylin 

 solution (haematoxylin 1 grm., acetic acid 2 c.c., water 100 c,e.). 

 Develop afterwards as by Pal's method. This is a very 

 good method for quickening the hardening process, and for 

 sections which have been too long in alcohol after potassium 

 bichromate." 



694. FLECHSIG (Arch. f. Anat. u. Phys., Physiol. Abth., 1889, p. 537 ; 

 Zeit. f. wiss. Mik., vii, 1, 1890, p. 71 ; Journ. Roy. Mic. Soc., 1890, p. 538) 

 stains sections for three to eight days at a temperature of about 35 C. in a 

 solution of redwood (Rothholz, Brazil-wood). This is prepared (after BBANCA) 

 by dissolving 1 grm. of extract pur. of Japanese ledwood in 10 grms. of 

 absolute alcohol, and adding 900 grms. of water, 5 grms. of saturated solu- 

 tion of Glauber's salt, and 5 grms. of saturated solution of tartaric acid. 



