One of the great problems attendant upon the study 
of fossil plants with structure preserved is the difficulty 
involved in using high magnifications. The use of oil im¬ 
mersion objectives has hitherto been impractical. 
Several months ago, my colleague, Doctor A. Orville 
Dahl suggested the possibility of preparing a peel and 
subsequently freeing the occluded plant structures by 
redissolving the nitrocellulose. With this purpose in 
mind, I tried a number of procedures on various types 
of fructifications with encouraging results. 
A peel containing spores or pollen grains is carefully 
cropped with scissors and the selected portion is set aside 
for the transfer of the spores or pollen. Then a glass slide 
is thoroughly cleaned and moistened with a droplet of 
albumen (egg-white). The slide is air dried in a dust-free 
place for twenty minutes and then the peel is impressed 
in the albumen. The glass slide with the peel adhering 
to it is placed in a container of butyl acetate and is per¬ 
mitted to stand until all of the nitrocellulose has been 
dissolved. This is usually accomplished in three or four 
hours. When this transfer of the spore or pollen grain 
has taken place, that is, the body is now imbedded in 
the albumen instead of the nitrocellulose, the slide is re¬ 
moved from the solvent and is gently dipped into butyl 
alcohol. The albumen can then be completely dehydrated 
with absolute ethyl alcohol, and the fossil quickly cover¬ 
ed with balsam and a cover glass. Such a permanent 
mount can be studied in the same manner as a similar 
preparation of parts of extant plants. 
With this new tool, paleobotanists may be able to 
find gametophytes among those extinct ferns which are 
supposed to have been endosporal in development, and 
to investigate the male gametophytes of the early seed 
plants. 
[36] 
