78 METHODS OP MICROSCOPICAL RESEARCH. 



beautiful gradations of tints, from the deepest violet 

 to the most delicate blue, which by careful treat- 

 ment are produced by a good logwood stain, give a 

 sense of relief to the eye during prolonged observa- 

 tions which no other tints, perhaps, afford. No 

 more beautiful stainings have been produced than 

 those obtained by a prolonged immersion (say for 

 twelve hours) in a logwood solution, made according 

 to the first formula given below, and diluted to 

 a light violet colour, which after the sections 

 so stained have lain in tap water for twenty- 

 four hours will result in a most beautiful blue 

 ground colour with the nuclei of a darker blue. 

 Let them then be placed in spirit for half an 

 hour, and then in a stain made from 2 parts of a 

 saturated alcoholic solution of rubin and 1 part of a 

 saturated alcoholic solution of yellow eosin diluted 

 with alcohol, until it becomes of a delicate pink 

 shade, and in which the sections may be kept until 

 they are " cleared " and mounted. The sections 

 thus treated will be found to be distinctly triple- 

 stained in blue, crimson and orange colour without 

 diffuseness and with perfect differentiation, and if 

 mounted in " xylol balsam' 9 they will prove quite 

 permanent. 



Carmine and picro-carmine also are invaluable as 

 nuclear stains, whilst for many tissues, and especially 

 for most vegetable tissues, they are preferable to 

 logwood, and, when mounted in a suitable medium, 

 sections stained with them prove equally beautiful 

 and permanent preparations. 



A carefully selected list of formulas for the most 

 important and reliable staining re-agents is here 

 appended, the proper media in which sections 



