CHAPTER XXXIII. 453 



878. Congo Red. NISSL (Ztschr. wiss. Mikr., iii, 1886, p. 398) stains for 

 three days in Congo red (5 parts to 400 of water) and differentiates in 

 alcohol with 3 per cent, of nitric acid. 



Other Methods. KOTHIG'S Vital-Scharlach Vm Counterstain 



(Neurol. Centrbl., xxxiii, 1914, p. 219, and xxxiv, 1915, p. 265). 

 Sections stained and differentiated by Weigert-Pal's method are 

 kept for twenty-four hours at room temperature in a counterstaining 

 fluid consisting of 90 c.c. of distilled water and 10 to 20 c.c. of a 

 solution of Vital-Scharlach VIII, saturated at room temperature. 

 They are then washed in distilled water for fifteen minutes and 

 differentiated in 70 per cent, alcohol for from one or two hours up to 

 twenty-four, when the celloidin will be found to be colourless. 

 After another wash in 96 per cent, alcohol, sections are mounted as 

 usual. Nerve cells and their processes, as well as axis-cylinders red, 

 the latter being visible within the deep blue myelin sheaths. 



The method does not succeed if the sections were previously 

 treated with an osmic acid solution. Vital-Scharlach VIII may 

 also be used as a general stain, in which case the finished preparations 

 are similar to those obtainable by the usual carmine stains. 



PALADINO'S palladium chloride methods ; see Rendic R. Accad. 

 Scienze, Napoli, iv, 1891, p. 14 ; Arch. Ital. BioL, xvii, 1892, p. 145, 

 and xix, 1893, p. 26. 



For WOLTER'S vanadium chloride process, see next chapter. 



ZOSIN'S magenta red method ; see Neurol. Gentrlb., xxi, 1902, p. 207. 



PERUSINI'S remarks and methods for the study of the white substance 

 of the spinal cord : see Journ. Psychol. Neurol., xix, 1912, p. 61. 



