STAINS AND STAINING 
61 
alcohol. We have not found Grtibler’s cyanin at all satisfactory with 
the foregoing formula. With the general formula the Griibler’s 
cyanin will not dissolve. We use a cyanin prepared by H. A. Metz 
& Co., 122 Hudson Street, New York. This cyanin dissolves com¬ 
pletely when made up according to the general formula. It stains 
rapidly, 5 to 10 minutes usually being sufficient. Chromosomes take 
a deep blue, but the spindle is only slightly affected. Lignified 
structures stain blue, while cellulose walls are scarcely affected and 
the stain is easily washed out. 
Iodine Green.—Use a 1 per cent solution in 70 per cent alcohol. 
Stain for an hour, rinse in 70 per cent alcohol, dehydrate in 95 per 
cent alcohol and absolute alcohol, clear in xylol or clove oil, and 
mount in balsam. If the stain washes out too rapidly and does not 
give sufficient differentiation, stain longer, over night or even 24 hours. 
Lignified structures stain green, but, after proper washing, 
cellulose is scarcely affected. A bright green may be left in the 
chromosomes after all the stain has been washed out from the spindle. 
Acid fuchsin, erythrosin, and eosin are good contrast stains 
for mitotic figures. Acid fuchsin or Delafield’s haematoxylin are 
good for cellulose walls. 
Light Green (Licht Griiri ).—Light green is an acid stain, soluble 
in water, alcohol, or clove oil. It stains quickly and forms a sharp 
contrast with safranin or Magdala red. 
Stain in safranin and then, with little or no washing out, stain in 
a weak alcoholic solution of acid green (about 0.2 g. in 100 c.c. of 
95 per cent alcohol). From 20 seconds to about 1 minute may be 
sufficient. The green rapidly reduces the safranin, and consequently 
the staining must not be too prolonged. A successful preparation 
should show red chromosomes and green spindle. Lignified walls 
should be red and cellulose walls green. 
Malachite Green.—A 1 to 3 per cent aqueous solution is good for 
cellulose walls. The stain contrasts well with Congo red. 
Methyl Green.—A 1 per cent solution in water is good for staining 
lignified structures. Lee recommends that the solution be acidulated 
with acetic acid. This is not necessary for staining lignified mem¬ 
branes nor for staining chromosomes. Methyl green has long been 
a favorite stain for living tissues. It is more easily controlled than 
iodine green, especially in double staining to differentiate lignified 
and cellulose walls. 
