470 NISSL. GRANULES 



1002. Suggestions Regarding the Carrying-out of Nissl's Method. 



For the fixation of tissues, alcohol, formalin, sublimate or mixtures 

 of these may be employed. The results are, however, better if 

 tissues are placed for some time in alcohol after fixation with one 

 of the above fluids. Acid solutions or chrome salts should be 

 avoided. Old formalin material can be used for carrying out the 

 Nissl method and its modifications if it is treated for twenty-four 

 hours with ammoniated tap-water before being transferred to 

 alcohols. 



Although the bichromates of potassium and ammonium and all 

 mixtures containing chromic salts should be avoided for cytological 

 investigations in Nissl's sense, sections from material fixed for a 

 short time (twenty hours) in the mixtures of Orth, Helly or 

 Maximow are well stained by Giemsa's fluid if this is employed 

 as described in § 877, and p. 400, 



Sections of material which were not fixed in alcohol and of 

 imbedded tissues, however fixed, stain, as a rule, very poorly by 

 Nissl's soap-methylen-blue method ; but excellent results can be 

 obtained by staining such sections with watery solutions (generally 

 0-5 to 1 per cent,) of toluidin blue, thionin, Unna's polychrome 

 methylen blue, cresyl violet, dahlia violet, vesuvine, neutral red, 

 magenta red, Azur II, and the like. 



Particularly good results are sometimes obtained by restaining 

 the sections a second and a third time after having differentiated 

 them completely each time (Da Fano, Proc. Physiol. Soc, Jov.rn. 

 Physiol., liv, 1920-21, p. 114), 



All specimens stained by Nissl's method keep badly, but they 

 can be preserved practically unaltered for months or even years 

 if the following points are observed : (1) the anilin alcohol or 

 alcohol used for differentiation purposes should be pure and 

 completely removed by means of pure benzol before mounting 

 the sections ; instead of benzol, pure xylol can be used, though 

 not advised by Nissl ; (2) the xylol-colophonium should be 

 rather thick and prepared with pure xylol ; instead of colo- 

 phonium, Canada balsam can be used ; it is in any case important 

 that either the colophonium or the balsam should not be acid ; 

 some authors prefer thick cedar-wood oil or similar mounting 

 media ; (3) the mounted specimens must be carefully protected 

 from light, 



1003. Modifications of Nissl's Method. Bielschowsky and 

 Plien's Cresyl Violet Method {Neurol. Centrbl., xix, 1900, p. 1141). 

 Celloidin or paraffin sections of material fixed either in alcohol or 

 formalin, or sections made by the freezing method from formalin 

 material, are stained for twenty-four hours in a very diluted 

 solution of cresyl violet R,R,, prepared by adding 6 to 8 drops 

 of a concentrated aqueous solution to every 50 c,c, of distilled 

 water. After a quick wash in distilled water sections are brought 



