348 THE MICROSCOPIST. 



lime ( J- ounce to 1 pint of water) until thoroughly bleached. 

 Soak then in a solution of hyposulphite of soda (1 drachm 

 to 4 ounces water) for an hour, and after thoroughly wash- 

 ing in several changes of water transfer them to alcohol. 

 Prepare some red staining fluid by dissolving J a grain of 

 magenta crystals in 1 ounce of alcohol. Soak the speci- 

 men in this for thirty minutes, then rapidly rinse it in 

 alcohol and place in a blue fluid made by dissolving J 

 grain of anilin blue in 1 drachm of distilled water, adding 

 10 minims of dilute nitric acid and alcohol enough to 

 make 2 ounces. Let the specimen remain only two or 

 three minutes in this, rapidly rinse in alcohol, put in oil 

 of cajeput, thence into turpentine, and mount in balsam. 

 The principle of double staining depends on the affinity 

 which certain dyes have for certain cells. Thus, if sec- 

 tions stained in red or green anilin be soaked in alcohol, 

 and those stained by logwood in alum-water, the color 

 will leave the loose parenchyma and be retained by the 

 denser cells, while specimens stained in blue anilin if left 

 in alcohol, and those stained in carmine if left in water, 

 lose color more slowly in the parenchyma than in other 

 parts. 



Eosin-staining . Dilute solutions of eosin, an anilin 

 preparation, 1 part to 1000 of w T ater, has been proposed 

 for animal tissues, since the different parts are differenti- 

 ated by different tints. Sections are stained in a minute 

 to a minute and a half, then washed in water acidulated 

 slightly with acetic acid, and examined in glycerin; or 

 they can be mounted in balsam after the water is removed 

 (see page 80). 



CLASSIFICATION OF CRYPTOGAMIA. 



In addition to the classification given in previous chap- 

 ters, the following, chiefly compiled from the Micrographic 

 Dictionary ', may be useful: 



