54 
METHODS IN PLANT HISTOLOGY 
The anthers are teased out with nickled instruments.” A cover- 
glass is then added and sealed with vaseline. The preparation lasts 
only a few days, but is much superior to any obtained by the usual 
intra vitam processes. 
THE ANILINS 
Many of the most brilliant and beautiful stains yet discovered 
belong to this group. These stains are very numerous, but not so 
numerous as their names; for different names have been given to 
the same stain, and the same name has been given to different stains. 
Fortunately, the Committee on Standardization of Biological Stains 
is doing a good work in standardizing the nomenclature as well as 
the stains themselves. A valuable list of synonyms, with the pre¬ 
ferred designations, was published in Science, 57:743-746, 1923, 
and other references to the work of the commission are given in the 
Bibliography on page 341. 
General Formula.—Make a 10 per cent solution of anilin oil in 
95 per cent alcohol; when the anilin oil is dissolved, add enough 
water to make the whole mixture about 20 per cent alcohol; add 1 g. 
of cyanin, erythrosin, safranin, gentian-violet, etc., to each 100 c.c. of 
this solution. Solutions containing anilin oil do not keep as well as 
aqueous or alcoholic solutions. 
The anilins keep well in balsam, but not so well in glycerine. 
Xylol is a good clearing agent for all of them; but clearing in clove 
oil improves stains like gentian-violet, which are more or less soluble 
in clove oil. Even in such cases, xylol should follow the clove oil, 
or the preparation will fade. 
While the anilins are not as permanent as the haematoxylins, 
most of them keep fairly well if the staining has been carefully done. 
Preparations fade if exposed long to bright sunlight. Keep the slides 
in the box when not in use, and even when in use, do not leave them 
on the laboratory table, exposed to the sun. We have preparations, 
made more than 25 years ago, in which the safranin and gentian- 
violet are still bright; and others made more than 10 years ago, in 
which Magdala red and aniline blue have not faded. 
Some of the anilins are acid, some basic, and some are neutral. 
The rapidity with which sections must be transferred from one 
fluid to another makes many of them more difficult to manage than 
the haematoxylins or the carmines, but the stains are so valuable 
that even the beginner should spend most of his time with the anilins. 
