380 NEKVES. 



Axis-cylinder Stains. 



721. Amongst the chief methods for the study of the re- 

 lations of axis-cylinders or non-medullated nerve-fibres are 

 the gold methods given in Chaps. XII in Part I, and XXYII 

 and XXVIII in Part II. The method of Freud for nerve- 

 centres, which will be given in the next chapter, is also a 

 good one for the study of the topography of peripheral nerves. 

 But perhaps even more useful are the methods of GTOLGI given 

 above, and the very important methylen-blue impregnation 

 methods that have been described in Part I, Chap. IX. The 

 following are also serviceable methods. 



722. KUPFFER'S Method (Sitzb. math. phys. KL k. Bayr. Acad. Wiss., 

 1884, p. 446 ; Zeit.f. wiss. Mik., 1885, p. 106). A nerve is stretched on a 

 cork and treated for twenty -four hours with 0'5 per cent, osmic acid. It is 

 then washed in water for two hours and stained for twenty-four to twenty- 

 eight hours in saturated aqueous solution of Sauref uchsin ; after which it is 

 washed out for from six to twelve hours (not more in any case) in absolute 

 alcohol, cleared in clove oil, imbedded in paraffin, and cut. Sections are said 

 to show the axis-cylinder as a bundle of fibrils (stained red) floating in an 

 albuminous liquid. 



' 723. NISSL'S Method (Milnchener med. Wochenschr., 1886, p. 528 ; Zeit. 

 f. wiss. Mik., iii, 3, 1886, p. 398). Bichromate objects to be treated as follows : 

 Alcohol of 95 per cent. ; aqueous solution of Congo red, of 5 : 400 strength, 

 seventy-two hours ; alcohol of 95 per cent., five to ten minutes ; alcoholic 

 solution of nitric acid of 3 per cent, strength, six hours ; alcohol, fire 

 minutes ; clove oil ; balsam. 



724. ALT (Munch, med. Wochenschr., 1892, No. 4 ; Zeit. f. wiss. Mik., 

 ix, 1, 1892, p. 81) stains for a couple of hours in solution of Congo in abso- 

 lute alcohol, and washes out with pure alcohol. The results are said to be 

 specially adapted to the study of peripheral axis-cylinders. SCHIEFFEBDECKER, 

 reporting on the method, does not recommend it. SQUIRE (using a 2 per 

 cent, aqueous solution) says it is one of the best stains he has tried. 



725. Similar to this is one of the methods of KEHM (Munchener med. 

 Wochenschr., 1892, No. 13 ; Zeit. f. wiss. Mik., ix, 3, 1893, p. 390). Sec- 

 tions are stained for a few minutes in concentrated aqueous solution of 

 Congo, washed in alcohol, and treated for ten minutes, until they become 

 blue, with alcohol acidulated with hydrochloric or nitric acid, then cleared 

 with origanum oil and mounted. A sharp axis-cylinder stain with consider- 

 able richness of other detail. 



But REHM prefers the following simple process : Sections of alcohol- 

 hardened material are placed for one to two days in an aqueous solution of 

 hffimatoxylin of 0'5 per cent, strength, then washed out in aqueous solution 

 of carbonate of lithia (strength not given) until no more colour comes away 



