d or sun-dried fresh
driers, and the pressure renewed, while the moist sheets are spread out
to dry, so as to take their turn again at the next shifting. This course
must be continued until the specimens are no longer moist to the touch.
Good and comely specimens are either made or spoiled within the first
twenty-four or thirty-six hours. After that, when plenty of driers are
used, it may not be necessary to change them so frequently.

564. Succulent plants, which long refuse to part with life and moisture,
and Spruces and some other evergreens which are apt to cast off their
leaves, may be plunged for a moment into boiling water, all but the
flowers. Delicate flowers may be encased in thin tissue paper when put
into the press. Thick parts, like the heads of Sunflowers and Thistles,
may be cut in two or into slices.

565. Dried specimens may be packed in bundles, either in folded paper or
upon single half-sheets. It is better that such paper should not be
bibulous. The packages should be well wrapped or kept in close cases.

566. =Poisoning= is necessary if specimens are to be permanently
preserved from the depredation of insects. The usual application is an
almost saturated solution of corrosive sublimate in 95 per cent alcohol,
freely applied with a large and soft brush, or the specimens dipped into
some of the solution poured into a large and flat dish; the wetted
specimens to be transferred for a short time to driers.

Sec. 2. HERBARIUM.

567. The botanist's collection of dried specimens, ticketed with their
names, place, and time of collection, and systematically arranged under
their genera, orders, etc., forms a _Hortus Siccus_ or _Herbarium_. It
comprises not only the specimens which the proprietor has himself
collected, but those which he acquires through friendly exchanges, or in
other ways. The specimens of an herbarium may be kept in folded sheets
of paper; or they may be fastened on half-sheets of thick and white
paper, either by gummed slips, or by glue applied to the specimens
themselves. The former is best for private and small herbaria; the
latter for large ones which are much turned over. Each sheet should be
appropriated to one species; two or more different plants should never
be attached to the same sheet. The generic and specific name of the
plant should be added to the lower right-hand corner, either written on
the sheet, or on a ticket pasted down; and the time of collection, the
locality,