30 
METHODS IN PLANT HISTOLOGY 
until the liquid fails to clear up completely, a very slight amber 
remaining for an hour or even permanently. After material fixed 
in the alcoholic solution has been washed in 50 per cent alcohol for 
an hour or more, add the iodine solution used in testing for starch 
or even add, drop by drop, tincture of iodine, until the color fails 
to disappear. With unicellular forms, filamentous forms, and thin 
things, like fern prothallia, such washing is likely to be sufficient, 
but with more bulky material, which is to be sectioned, the crystals 
may appear in the paraffin ribbon. In such cases, the slide should be 
dipped for a minute in the iodine solution just before staining. 
Camphor may be used instead of iodine to hasten the washing, but 
it does not give any color reaction. 
Material should be imbedded as soon as possible, since it gets 
brittle if allowed to remain in alcohol. 
Kinoplasmic ^structures do not stain well with gentian-violet, 
but safranin and the haematoxylins stain almost as well as after 
chromic-acid mixtures, and the carmines give their most brilliant 
stains, as a result of the formation of mercuric carminate. 
The following formulas are merely suggestive: 
a) Corrosive Sublimate and Acetic Acid.— 
Corrosive sublimate. 3 g. 
Glacial acetic acid. 5 c.c. 
Alcohol (50 per cent) or water. 100 c.c. 
b) Corrosive Sublimate, Acetic Acid, and Formalin.— 
Corrosive sublimate . 4 g. 
Glacial acetic acid. 5 c.c. 
Formalin. 5c.c. 
Alcohol (50 per cent) or water. 100 c.c. 
This is our favorite formula. For material which is to be 
mounted in glycerin, glycerin jelly, or Venetian turpentine, use the 
aqueous solution; for material which is to be imbedded, use the 
alcoholic. Cilia are caught and preserved; and even delicate 
organisms, like Volvox, do not collapse. 
c) Corrosive Sublimate, Acetic Acid, and Picric Acid.— 
Corrosive sublimate . 5 g. 
Glacial acetic acid. 5 c.c. 
Picric acid, saturated solution in 50 per cent 
alcohol. 100 c.c. 
