94 
METHODS IN PLANT HISTOLOGY 
tedious and gives better results than have been secured by the 
method just described. Fix in the chromo-acetic-osmic mixture (d), 
described on page 26. Stain some prothallia in iron-alum haema- 
toxylin and some in Magdala red and anilin blue. When both have 
reached the thick turpentine, fine preparations can be made by 
mounting prothallia from both lots under the same cover. 
Sori of Ferns.—Instructive mounts of sori or of individual 
sporangia may be made without sectioning. It is better to choose 
ferns with thin leaves, since leaves thicker than those of Asplenium 
thelypteroides are likely to be unsatisfactory. If this fern is at hand, 
cut off several of the small lobes which bear three to six pairs of sori. 
Fix in chromo-acetic acid; wash in water; stain in Delafield’s 
haematoxylin, or omit staining altogether; pass through a series of 
alcohols, allowing each grade to act for at least 10 minutes; clear in 
clove oil, and mount in balsam. If the sori have begun to turn brown, 
better views of the annulus will be obtained without staining. 
Mosses and Liverworts.—Nearly all mounts are more successful 
by other methods, for which the student should consult the chapters 
on Bryophytes (chaps, xix and xx). Excellent mounts of the peristome 
of the moss can be made as follows: From fresh or preserved capsules 
cut off the peristome just below the annulus. Treat with 95 per cent 
alcohol 1 minute, absolute alcohol 2 to 5 minutes, clear in clove oil or 
xylol, and mount in balsam. It is a good plan to put at least three 
peristomes on a slide, one with the outside up, one with the inside up, 
and another dissected to show details of the teeth. 
Fairly good unstained mounts of the archegonia and antheridia 
of small mosses can be obtained by following the directions for 
mounting the sori of ferns. 
Beautiful and instructive mounts of the more delicate foliose 
Jungermanniaceae can be made by staining lightly in Delafield’s 
haematoxylin whole plants, or pieces as long as can be covered con¬ 
veniently. The method is that just given for fern prothallia. The 
mount should show both dorsal and ventral views. 
The Epidermis shows its best surface views without sectioning. 
Select some form with large stomata, like Lilium or Tulipa, strip 
pieces of epidermis from both sides of the leaf, and place them imme¬ 
diately in absolute alcohol for 1 or 2 minutes. Stain in Delafield’s 
haematoxylin; after this stain is satisfactory and all acid has been 
washed out, stain for 1 or 2 minutes in aqueous eosin, erythrosin, or 
