REAGENTS 
27 
hydrogen, even 20 per cent. The peroxide should be in water, if one is 
following it by an aqueous stain, but may be in 50 per cent alcohob 
if it is to be followed by an alcoholic stain. Yamanouchi has used 
chlorine for bleaching, and the results are fully equal to those obtained 
with peroxide of hydrogen, and the chlorine is cheaper. Make the 
bleacher as follows: Place some potassium chlorate crystals—a 
group about as large as a grain of wheat—in the bottom of a 100 c.c. 
Stender dish; add one drop of 25 per cent hydrochloric acid in water; 
immediately fill the Stender full of 30 per cent alcohol and thus 
dissolve the fumes in alcohol. This will bleach sections in 10 minutes, 
or even less. Wash in 30 per cent alcohol 2 or 3 hours before stain¬ 
ing. Trondle uses 1 per cent chromic acid in water for bleaching; 
it is slow, requiring about 8 hours, but he maintains that material 
stains better than after bleaching with peroxide of hydrogen. Accord¬ 
ing to Miss Merriman, the linin in the nuclei of onion root-tips is 
not so well preserved in this solution, but the arrangement of the 
chromatin granules is brought out with greater distinctness. 
Flemming’s safranin, gentian-violet, orange combination gives excel¬ 
lent results after this reagent. 
g) Flemming’s Fluid (weaker solution) .— 
{ 1 per cent chromic acid. 25 c.c. 
1 per cent acetic acid.lOc.c. 
Water. 55 c.c. 
B. 1 per cent osmic acid. 10 c.c. 
As in case of the stronger solution, mix A and B only as needed for 
immediate use. 
Many prefer the weaker solution, because the blackening is not 
so extreme and material does not become quite so brittle. Some 
allow the solution to act for an hour and then transfer the material to 
solution A for about 24 hours. This secures the rapid killing, 
which is the principal virtue of the osmic acid, and avoids the dis¬ 
agreeable blackening, so that little or no bleaching may be necessary. 
h) Benda’s Fluid.— 
1 per cent chromic acid. 16c.c. 
2 per cent osmic acid. 4 c.c. 
Glacial acetic acid. 2 drops 
This modification of Flemming’s stronger solution has been used 
in various investigations upon chromatin. 
