CHOICE AND USE OF APPARATUS 



chemicals act very quickly, and staining takes place 

 in a few minutes ; others act slowly, and with them 

 it is necessary to subject our specimens to their action 

 for hours or even days. Then again, it is obvious 

 that large specimens take longer to stain than small 

 ones, hard objects are not so readily acted upon as 

 soft ones. Experience alone will show what is re- 

 ; quired in various cases. 



Suppose, for example, we desire to stain a section 

 in Carmalum, a mixture of Carminic Acid 1 grain. 

 Alum 10 grains, hot distilled water 200 c.c. We take 

 three watch glasses, in one we place a few drops of 

 our stain, in another water, and in the third alcohol. 

 Our section is placed in the watch glass containing 

 the carmalum and is left there for about two minutes, 

 then with the help of a small brush it is transferred 

 for a similar period to the watch glass containing 

 water, and finally it is placed in the alcohol. From 

 the last watch glass it may be transferred to glycerine 

 jelly on a slide and mounted as already described; 

 Carmalum stains our section a beautiful pink. 



There is a temptation to buy a large stock of stains 

 of all hues and of varied composition. The tempta- 

 tion should not be allowed to get the better of us. 

 In our early days at any rate, we shall do far better 

 if we use but few stains and learn to understand their 

 peculiarities. 



The most useful selection for the beginner will 

 comprise Haematoxylin, Safranin, Eosin, Carbol- 

 Fuchsine, Methylene Blue, and Carmalum. These 

 should all be obtained ready for use : this will save 



805 U 



