NERVOUS SYSTKM CYTOLOCHCAL METHODS. 403 



in absolute alcohol, and imbedded (they must be protected from the 

 light whilst in the chloroform through which they are passed into 

 paraffin, or whilst in celloidiii). Sections are made and mounted in a 

 resin or in neutral glycerin. 



This method has given splendid results with Hirudinea and some 

 other invertebrates, but I believe has not yet been successful with 

 vertebrates. 



774. Neurofibrils, Berlin Blue (S. MEYER, Anat. Anz., xx, 1902, p. 

 535). Material is best fixed in 10 per cent, formol, then mordanted for 

 eight to twenty days in ferrocyaiiide of potassium of 2 5 per cent, (or this 

 salt may be added to the fixative), then put for two to four days into 

 iron alum of 10 per cent. Wash for several hours, imbed in paraffin, and 

 mount sections in balsam. Besides iieurofibrils, the sheath of Schwann 

 and the constrictions of Ranvier are stained. Like the Golgi chrome- 

 silver process, this method gives a partial impregnation, only certain 

 elements taking on the stain. 



775. The Methylen blue intra vilam method is important, 

 see the processes of APATHY, DOGIEL, and BETHE in Chapter 

 XVI. 



776. The methods of Cox for the fibrils of spinal -ganglion cells, Zeit. 

 iviss. Mik., xiii, 1896, p. 498, and Anat. Hefte, x, 1898, p. 98, seem to be 

 definitively superseded. 



777. Golgi's INTRA-CELLULAR NETWORK. For the study of 

 his apparato reticolare interno, GOLGI (Verh. Anat. Ges., xiv, 

 1900, p. 174) uses a mixture due to VERATTI, consisting of 



5 per cent, bichromate . . .30 parts 



0*1 per cent, platinum chloride . . 30 



1 per cent, osmic acid . . 15 to 30 ,, 



and after hardening therein puts (for a time varying from a 

 few hours to ten days) into a mixture of 1 part of bichro- 

 mate of 3 or 4 per cent, with two of saturated solution of 

 sulphate of copper, and thence into silver nitrate of 0*8 to 1 

 per cent. See further Verh. Anat. Ges., xiv Vers._, 1900, 

 p. 174. 



More recently (Arch. Ital. BioL, xlix, 1908, p. 272 ; Mou. 

 Z. Ital., xix, 1908, p. 263) he fixes for six to eight hours in 

 a mixture of equal parts of 20 per cent, formol, saturated 

 solution of arsenious acid, and alcohol of 96 per cent., and then 

 puts for one to three hours (or days) into nitrate of silver of 

 1 per cent. He then reduces in any developer, usually 20 grms. 



