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grow in close contact with the earth, it is often desirable to preserve intact 
a thin layer of the soil, so as to hold the plant together. This is accom- 
plished by a coating of mucilage applied to the underside while the earth is 
moist. 
There are several methods in use among students of lichens, for pre- 
serving and arranging their specimens. Different circumstances and 
requirements make different ways preferable. A favorite way to keep the 
specimens is in pockets, which are made as follows: Fold a piece of paper (7 
by 9 inches is a convenient size) so the under part shall project about three- 
quarters of an inch beyond the upper; fold the projecting part over the other 
to make the top of the pocket: turn the pocket over and fold back the right 
and left edges for about three-quarters of an inch, and it is finished. Such 
pockets, if of uniform size, may be arranged in a box or tray like the cards 
of a card catalogue. When thus used, writing the name of the species at 
the top of the pocket, facilitates reference. This method of keeping speci- 
mens affords a way of making a good working collection with small outlay of 
time and labor. If it is desired to incorporate the specimens in a general 
herbarium, the pockets may be attached to the regular species-sheets by 
means of small ribbon pins, or with a spot of glue at the back. The chief 
objection to using pockets is that the specimens are not displayed. To ac- 
complish this, specimens are glued onto pieces of rather stiff paper of conveni- 
ent size (room being allowed for labeling), and then these pieces of paper are 
pinned to the herbarium sheets. In thus mounting lichens which have a dis- 
tinct under side it is important that the character of this as well as the upper 
side be exhibited. Keeping specimens in scrap-books is hardly to be recom- 
mended, unless for a very small collection, since this method does not facili- 
tate a systematic arrangement and interpolation of additions. 
Rock specimens which are too bulky to be incorporated with the others 
may be kept like minerals in trays or in a cabinet. An approved way for 
large collections is to have pasteboard boxes made of such a size as to go 
with the rest of the collection in the herbarium case. 
All specimens should be labeled with the botanical name of the species, 
the locality, habitat, and date of collection (if desired) together with the 
name of the collector (if other than the owner). 
Having collected as many as possible of the common species of the 
neighborhood and prepared them conveniently for examination, the student 
is in position to begin an examination of their form, structure and classifica- 
tion. 
A good deal may be learned about them without other aid than the sim- 
ple microscope already recommended: but for thorough study of lichens, a 
good compound microscope, magnifying three to four hundred diameters, is 
essential. We shall consider, however, at this time chiefly such features as 
involve in their study comparatively simple microscopical manipulations. 
Cambridge, Mass. 
(To be continued.) 
■ p. Uif? 
