OF THE HERBARIUM. 
193 
Although by this arrangement the difficulty of getting at 
the specimens is undoubtedly increased, still the advantages 
are great, where (as I observed before) the fascicles are not 
in constant requisition ; it saves the specimens from dust, it 
keeps the wrappers in good order, and it helps to ward off 
the ravages of insects. 
I referred just now to the need of selecting some system- 
atic work as a guide in the arrangement of the herbarium. 
This is easily done as regards the flowering plants and the 
higher Cryptogamia ; there are works enough published to 
satisfy the taste of every collector, whatever his views may 
be, whether Linnsean, Jussiasan, Candollean or Lindleyan, 
But this, I regret to say, is far from being the case with the 
lower Cryptogamia, the Lichens, Fungi, and Algas. Inde- 
pendently of the fact, that the systems hitherto arrived at 
are far from perfect, there is the additional circumstance, that 
science in its onward strides is ever bringing new species to 
light, or compelling the re-arrangement of those with which 
we are already acquainted. Consequently, we must either 
find room in our catalogue for species of whose existence 
we had no conception a short time before ; or, on the other 
hand, we must be prepared, in consequence of a deeper 
insight having been gained into their structure and habits, 
to separate species, hitherto closely combined, and not un- 
frequently to place them in distinct genera. 
To meet these difficulties a certain elasticity must be 
allowed to the catalogue, so as to permit of the names of 
species being introduced or removed without disturbing its 
general arrangement. For this purpose quarter-sheets of 
foolscap paper are prepared; one, two, or three for each genus, 
according to its size. The generic name, with its reference 
number, being placed at the head of the paper, the species 
are added in due order beneath, a considerable space being- 
left between each name to admit of others being introduced. 
In this way new species can be inserted in their proper 
places, without having recourse to endless interpolations, 
which disfigure the page and confuse the raider. 
o 
