68 MOUNTING AND PREPARATION OP OBJECTS. 



are taken from the spirit and water, and placed in 

 the staining solution ; a flat tin spoon having a. hole 

 in the centre of its rounded extremity and its handle 

 bent at right angles, will be found useful for this 

 purpose. 



The best staining fluid for all preparations in- 

 tended for microscopical photography is Beale's 

 carmine solution. Klein recommends the following 

 modification : 



Powdered Carmine, 2 grammes, 

 rub up with a few drops of distilled water and add 



Liquor. Ammon. Fort., 4 c.c. 

 Distilled Water, 48 c.c. 



Shake up well and place in a bottle secured with 

 an india rubber or greased cork to prevent evapora- 

 tion. Glass stoppers are useless for this purpose and 

 should only be used for acids. 



When required one drop is added to 10 or 20 of 

 water. If the tissue is very hard or has been kept a 

 long time in Muller's fluid, a stronger solution will 

 be required, and the vessel containing the staining 

 fluid with the sections must be accurately closed, as 

 its penetration depends to a considerable degree on 

 the quantity of ammonia. If however the sections 

 are fresh one drop is sufficient and the greater part 

 of the ammonia should be allowed to evaporate 

 before the addition of water. The proper amount of 

 staining requires considerable judgment to deter- 

 mine, but the more dilute the solution, the easier it 

 becomes and the greater the differentiation of tissue 



