J. W. GROVES ON SECTIONS OF ANIMAL TISSUES. 239 



the older it is the better are the results obtained with it. It is pre- 

 pared thus : — 



1. Make Saturated Solutions of Alum, and Calcium Chloride, in 

 proof spirit. 



2. Mix in the proportions of eight of the former to one of the 

 latter. 



3. Pound a small piece of Ext. Hoematoxyli (the older the 

 better) ; add to it the mixed solution, and agitate. 



4. After two days decant, when it may be used at once, though 

 better after keeping. 



A watch glass should be filled with water, and a few drops of this 

 solution added, till the fluid acquires a mauve tint. Into this the 

 sections may be placed, and should remain for 24 hours or more. 



The second is S chafer's Acid Logwood Solution, which is especially 

 useful for certain structures, as tendon cells, &c, which could not be 

 so well shown by neutral or alkaline solutions. It is thus pre- 

 pared : — 



A one per cent. Solution of Acetic Acid is coloured by the addi- 

 tion of 1*3 of its volume of Logwood Solution. 



The Anilin Dyes, whether in aqueous or alcoholic solution, gives 

 good results. The best are : — 



Roseanilin or Magenta (gr. i. to Alcohol ^i.), red. 



Acetate of Mauvein (grs. iv., Alcohol ^i., acid Nitric trii.), blue. 

 Anilin Black (gr ij., Water Ji.), grey-black. 



Nicholson's Soluble Blue (gr. -i-, Alcohol Ji.,and Nitric ttjjj.), blue. 



These, as other stains, should be used weak ; but the chief point 

 to be careful about is, that after the sections are stained they should 

 be passed through alcohol and oil of cloves as rapidly as possible, 

 otherwise the colour will be dissolved out before they reach the 

 balsam. 



Heidenhain, in speaking of the use of Anilin Dyes, says : — " The 

 sections, upon removal from alcohol, should remain for a day in a 

 four per cent, neutral aqueous solution, in a moist place, and then 

 be immediately mounted in glycerine and cemented." 



Some of the Anilin Dyes are but sparingly soluble in alcohol, 

 whereas they dissolve readily in water. Their colour, as a rule, is 

 increased by acetic acid, but removed by ammonia. There are, 

 however, some exceptions. 



The use of benzole for clearing instead of clove oil fixes the colours 



