SPECIAL STAINS. 335 



Water . 40 parts. 



Saturated aqueous solution of methylen blue . 24 

 5 per cent, solution of borax .... 16 



(Mix, let stand a day, and filter). 



The sections are then washed either in water or alcohol until the grey 

 matter can be clearly distinguished from the white, are cleared with cedar 

 oil, and mounted in balsam. Nerve-tubes are stained blue, ganglion-cells 

 greenish, nuclei of neuroglia blue. Micrococci are stained, if any be present 

 in the tissues. The preparations are not perfectly permanent. 



8 afranin followed by methylen blue gives a very special stain of spinal 

 cord. The method is due to ADAMKIEWICS (Sitzb. k. Acad. Wiss. Wien, 

 Math. Naturw. Kl., 1884, p. 245 ; Zeit. f. wiss. Mik., 1884, p. 587). 

 Sections are washed first with water, then in water acidified with a little 

 nitric acid, and stained in concentrated solution of safranin. They are then 

 treated with alcohol and clove oil till no more colour comes away, and are 

 brought back again into water, washed in water acidified with acetic acid, 

 stained in methylen blue, and cleared as before. The process is said to de- 

 monstrate the existence of " chromoleptic zones " which surround the grey 

 matter. Myelin (" erythrophilous substance " of Adamkiewics) is red, nuclei 

 of nerves, of neuroglia, and of vessels, violet. The erythrophilous substance 

 of pathological nerve -tubes does not take the stain, so that the method is 

 valuable for the study of degenerative changes. 



NIZIFOEOW (Zeit. f. wiss. Mik., v, 3, 1888, p. 338) modifies the foregoing 

 method as follows. The tissue is to be hardened in a chrome salt. It is not 

 to be washed in water afterwards. Sections are brought direct from alcohol 

 into the safranin stain, either concentrated aqueous, or Babes's solution, or a 

 solution in 5 per cent, carbolic acid. Stain for twenty-four hours. Bring 

 the sections into alcohol until the colour is sufficiently extracted for the 

 grey substance to be distinguished from the white. Then put them into a 

 weak (O'l to 0'2 per cent.) solution of chloride of gold or platinum or any 

 metallic salt. They are to be left in this until the grey substance just begins 

 to get a violet tone (not longer). They are then well washed in water, and 

 put into alcohol until the rosy violet of the grey substance becomes dis- 

 tinctly marked off from the red of the white substance. Clear with clove 

 oil, wash out the clove oil thoroughly with xylol (this is absolutely necessary 

 for the permanence of the preparations), and mount in balsam. Nikiforow 

 says that this method gives much sharper and more certain results than that 

 of Adamkiewics. 



Pnrjiiiriit., according to DUVAL, has a special action on nerve-tissue (espe- 

 cially spinal ronl) that has been hardened in bichromate of ammonia. Nerve- 

 cells and their processes, axis cylinders and connective-tissue fibrils remain 

 unstained ; whilst the nuclei of connective tissue and of capillaries stain 

 red (see IS'.i). 



Mounting. 



675. General Mounting Methods. Under this head it is to 

 IH not rd that it is often advisable to fix sections to the slide 



