FREEHAND SECTIONS 
95 
acid fuchsin; place directly into 95 per cent alcohol for a few seconds 
(merely to save the absolute alcohol), then into absolute alcohol for 
about 30 seconds, and then into clove oil. Mount in balsam. The 
epidermis is likely to curl and, unfortunately, patience seems to be 
the only remedy. In mounting, be careful to get pieces from both 
sides of the leaf, and be sure that the pieces are outside up. The 
inside of the epidermis is usually more or less rough, on account of 
the mesophyll torn off with it. Sedum purpurascens will show 
various stages in the development of stomata, even in epidermis 
stripped from mature leaves. The epidermis of the Sedums strips 
off very easily. If the large Sedum maximum is available, it is 
not difficult to strip off pieces 2 or 3 centimeters wide and several 
centimeters long. There is not much tendency to curl. The pieces 
may be spread out flat in a Petri dish, fixed in the chromo-acetic-osmic 
solution, just recommended for fern prothallia, or in this solution 
without the osmic acid. Wash in water, stain in Delafield’s haema- 
toxylin and eosin, or in safranin and gentian-violet. Then wash in 
water and run up through a series of alcohols—10, 20, 35, 50, 70, 85, 
and 95 per cent, about 2 minutes in each grade. If the gentian-violet 
is lost, stain for a minute in an alcoholic gentian-violet or in light 
green, for about 30 seconds; then transfer to clove oil, xylol, and 
balsam. This is a more tedious method, but it is worth the trouble. 
We have had the best results with the haematoxylin and eosin 
combination. 
Other Objects.—The cases just given will suggest other objects 
which might be mounted by such methods. Nearly all objects which 
used to be mounted in balsam without sectioning are now handled 
more successfully by the Venetian turpentine method. 
