240 CHAPTER XVII. 



same ground as those of DOGIEL, and give the same results. 

 MAYEK stained tissues for about ten minutes in a 1 : 300 or 

 400 solution of methylen blue in 0*5 per cent, salt solution, 

 rinsed in salt solution, and put up in the glycerin -picrate of 

 ammonia mixture given above, 328. He finds that by this 

 method all the essential result* of a nitrate of silver impreg- 

 nation may be produced by means of methylen blue. The 

 images are either positive or negative, as with silver. If the 

 stain be brought about by injection of the colour into the vas- 

 cular system, the positive impregnation is the more frequent ; 

 whilst if it have been brought about by the immersion of the 

 tissues (cornea), a negative image is more frequently 

 obtained. 



332. Toluidm Blue or Thionin as succedanea of methylen 

 blue. HAKRIS (Philadelphia Med. Journ., May 14th, 1898) 

 has found that there is no reaction of methylen blue that 

 cannot be equally well obtained with toluidin blue or thionin. 

 Indeed, he thinks that for nerves they may have some points 

 of superiority. For staining pieces of tissue he recommends 

 the following : 



Toluidm blue, O'l per cent. sol. in 



physiological salt solution . . 2 parts 



Ammonium chloride, 0'25 per cent, in 



water ..... 1 part 



Egg albumen . . . . 1 



For injections he uses 1 part of the dye to 1000 of physio- 

 logical salt solution. 



Any of the methylen blue fixing methods may be employed, 

 and the whole technique is the same. Harris's fixing method 

 has been given, 329. 



