152 Tue Microscope. 
Hydrochloric acid, - - - - - = =} part, 
Alcohol, (95 p..c.), -°- = = => ~ = epee 
Here it is allowed to remain until the lilac color changes 
to arose red. The muclei are particularly stained a bright red. 
PICROCARMINE STAINING. 
This is a double stain and is one of the most valua- 
ble of the coloring reagents. It is prepared by making a 
two per cent. solution of picrocarmine crystals in distilled 
water and filtering. Sections are seldom overstained in weak 
solutions of this reagent and they appear to improve with age. 
There are a large number of methods described for making the 
various solutions, all slight modifications of each other. Picro- 
carmine is valuable simply because the picric acid stains certain 
parts of the tissue yellow while the carmine imparts a red to 
the other parts. 
SULPHINDIGOTATE OF SODA STAINING. 
A saturated solution in distilled water is kept in stoppered 
bottles.. A beaker is partly filled with alcohol and enough of 
the soda solution added to impart a sky-blue color to it. The 
specimens are stained at the same time they are dehydrated. 
EOSIN STAINING. 
Tissues become stained in a few seconds when placed in 
this reagent. One part of eosin is added to 1,000 or 1,500 parts 
of water to make the eosin staining of commerce. It is made 
also in alcoholic solutions. After staining the sections are 
placed in a weak solution of acetic acid to remove the excess of 
color and fix the remainder. It is chiefly employed in double 
staining. 
ANILINE BLUK-BLACK STAINING. 
Dissolve one decigram in four c. c. of distilled water, and 
add to this 100 c. ce. of alcohol. This is a valuable staining for 
the neryous system. It gives a slate-gray color and stains very 
rapidly. 
DOUBLE STAINING PICROCARMINE. 
Picrocarmine, as already mentioned, stains certain parts of 
a tissue yellow and the other parts red. 
