Bulletin - United States National Museum - Smithsonian Institution

226 FLORA OF WASHINGTON AND VICINITY.
order-covers entirely until the herbarium becomes quite large and com-
plete. If the plants are kept in the natural order, you will soon become
so familiar with it that you will know within one or two partitions
where any plant is at any time.
It is not a mere accident that I have mentioned the general character
of the herbarium before mentioning the important process of mounting
plants. This is the finishing stroke of the whole work and should not
be hastily rushed into. A plant once mounted is generally fixed for all
time, and this should presuppose that it is not only known botanically,
but approved as a suitable specimen to adorn a cabinet. If rare, and
not likely to be found again, of course it should be mounted, even though
in itself imperfect, but in so far as the local flora is concerned, this is
very seldom the case.
For these and other reasons I would advise the postponement of the
work of mounting until after considerable experience has been acquired
in collecting and in general herbarium work. Some botanists never
mount plants. They urge with considerable force that this renders
them incapable of further study or examination, which any plant is
always liable to require. A specimen once mounted cannot be turned
over for the purpose of seeing the other side, where the two sides differ,
as is generally the case. To meet this objection, such plants when
mounted must be in duplicate, or so much so as to exhibit both sur-
faces. In the case of ferns, for example, nothing less than the mount-
ing of two entire specimens will generally sufiice.
Plants may be nicely kept without mounting by placing them in
double sheets of ordinary paper, and these in genus-covers the same
as if mounted. For increased safety, the fold of the species-cover may
be placed in the reverse position to that of the genus-cover. The name
of the species may then be written on the species-cover or on a white
slip and pasted on the outside of it, to save opening any that you
may not wish to examine. No two species should ever be i)laced in the
same cover, and where it is desired to preserve several specimens of the
same species these may go inside the species-cover on separate sheets of
paper.
The objection to this plan as a final one is that much handling, espec-
ially after the specimens become old, breaks them up and destroys
them. It is also more trouble and requires more time to open the
species-covers than to look at the mounted page. In the latter case
there is a quick method of looking a large genus through as you would