434 NERVOUS SYSTEM-SPECIAL METHODS. 



pyridine with a mixture of 3 parts of methyl-alcohol and 2 parts of 

 water. 



Mod. 9. Place sections in a mixture of equal parts of 20 per 

 cent, formalin and methyl alcohol for twenty-four hours ; wash in 

 redistilled water for six to twenty-four hours ; 2 per cent, silver 

 nitrate at 37 C. for twenty-four hours, etc., as before. 



Mod. 10. Place sections into 20 per cent, formalin for twenty- 

 four hours, transfer them, without washing, into a mixture of equal 

 spart of 20 per cent, formalin and methyl alcohol, etc., as in Mod. 9. 



Mod. 3 is particularly suitable for human material of young 

 individuals : Mod. 4 for adult subjects. Mods. 5 and 6 are useful 

 for the study of neurofibrils in the various elements of the cortex 

 cerebelli and for the staining of the granules. Mods. 7, 8 and 9 are 

 to be preferred for the demonstration of pericellular baskets and 

 nervous processes. Mod. 10 gives very complete stainings, and is 

 the most certain of all ; preparations are, however, fairly dark, and, 

 therefore, more suitable for general view. 



PERDRAU (Journ. Pathol. Bact., xxiv, 1921) has worked out a 

 modification which appears to be particularly suitable for the study 

 of the connective tissue in nervous organs. He washes pieces and 

 sections as in Da Fano's modifications, but without having recourse 

 to redistilled water. He then places sections for about ten minutes 

 in -25 per cent, potassium permanganate, washes, and treats them 

 as by Pal's modification of Weigert's myelin stain (see 857). After 

 another wash in distilled water, he transfers sections into 2 per cent, 

 silver nitrate, and continues as in Da Fano's Mod. 1. Nerve cells, 

 nerve fibres, neuroglia, etc., unstained ; connective tissue and 

 elastic fibres stained in various shades of purple-grey to black. 



84-3. Neurofibrils ; Other Methods. Cox's Method for fibrils of 

 spinal ganglion cells ; see Ztschr. wiss. Mikr. xiii, 1896, p. 498, and Anat. 

 Hefte, x, 1898, p. 98. 



S. MEYER'S Berlin blue, see Anat. Anz., xx, 1902, p. 535. 



LUGARO'S collargol (colloidal silver) method, see Monit. Zool. Ital., 

 xv, 1904, p. 353. 



JORIS' colloidal gold method has not been received with favour ; see 

 Bull. E. Acad. Med. Belg., xviii (S. iv), 1904, p. 293. 



SAND (C.R. Ass. Anat. Bruxelles, 1910 ; Bibliogr. Anat. Supp., 

 1910, p. 128, or Ztschr. wiss. Mikr., xxviii, 1911, p. 500) gives the 

 following as entirely certain for man, dog, cat, and rabbit. Speci- 

 mens of not more than 5 mm. in thickness are fixed for forty-eight 

 hours in a freshly prepared mixture of 90 parts of acetone and 10 

 of nitric acid, to be changed for fresh after half an hour, and once 



