26 
MAMMALIAN ANATOMY 
and float the sections, and the subsequent warming should 
continue until all wrinkles disappear, more water being 
added from time to time if needed, and care being taken not 
to melt the paraffine. The excess of water may then be 
removed with a bit of filter paper, and the slide set aside for 
24 hours to dry. Keep the identity of the slide by means of a 
temporary label. 
Staining and Mounting Sections on Slide. —After the slide is 
dry, remove the paraffine from the sections by first gently warming 
the slide over an alcohol flame until the paraffine begins to melt, 
and then placing the slide for a minute or two in a staining jar 
of xylol, which will dissolve the paraffine. As the stain which is 
to be used is an aqueous solution, with which, of course, oil will 
not mix, the xylol should be removed by placing the slide in a 
staining jar of 100% alcohol for a few minutes, first draining off 
the excess of xylol upon a piece of filter paper. 
From the 100% alcohol transfer the slide to a jar of 95% 
alcohol, and from this, without draining off the excess of alcohol, 
carry the slide in a horizontal position into a large, shallow dish 
of clean tap water in which it should be moved very slowly back 
and forth until all milkiness disappears and the water runs freely 
from the surface when the slide is lifted out of it. 
The sections are now impregnated with water and will take 
an aqueous stain. Place the slide in a jar of this stain (hema¬ 
toxylin, in this case) and leave it until a decided but not dark 
color has been imparted to it. From time to time take the slide 
out of the stain and rinse it in the water to see how deep a color 
has been acquired (cf. with the “sample” slide furnished by the 
laboratory). This process may take from one to ten minutes 
and must be carefully watched by the student that overstaining 
may not occur. 
When the staining is completed, carefully transfer the slide 
in a horizontal position, to the dish of tap water, where it should 
be left a few minutes in order that the slight alkalinity which tap 
water usually possesses, may change the reddish tinge of the 
sections to a bluish purple. Drain and wipe off the excess of water 
from the slide, and transfer the slide successively to 95 % and 100% 
alcohol, to dehydrate it. 
