While the two series above mentioned have for their object the diffusion of scientific knowledge, the next ministers mainly to its advancement, so that between them the twofold object of a National Museum of Natural History is carried out.
Reserve or Study Systematic Series.
III. The Reserve or Study Systematic Series contains the exceedingly numerous specimens (in many groups the great bulk of the collection) showing the minute distinctions required for working out the problems of variation according to age, sex, season and locality, for fixing the limits of geographical distribution, or determining the range in geological time: distinctions which, in most cases, can only be appreciated when the specimens are kept under such conditions as to admit of ready and close examination and comparison. It is to this part of the collection that naturalists resort to compare and name the animals and plants collected in exploring expeditions, to work out natural-history problems, and generally to advance the knowledge of science. In fact, these reserve collections, occupying comparatively little space, kept up at relatively small cost, and visited by comparatively few persons, constitute, from a scientific point of view, the most important part of the Museum; for by their means new knowledge is obtained, which, given forth to the world in the form of memoirs and books, is ultimately diffused over a far wider area than that influenced even by the exhibited portions of the Museum. Indeed, without the means of study afforded by the reserve series, the order displayed in the arrangement of the exhibition galleries, and the instruction which may be gleaned from the same, would not be possible.
It is important to bear in mind that if all the specimens required for enlarging the boundaries of knowledge were displayed in the public galleries, so that each could be distinctly seen, a museum many times larger than the present one would not suffice to contain them; the specimens themselves would be inaccessible to those capable of deriving instruction from their examination, while, owing to the effects of exposure to light upon preserved natural objects, many would lose their chief characteristics. This portion of the collection must, in fact, be treated as are the books in a library and used for consultation and reference by accredited students.[4]
In some parts of the Museum the reserve collections are contained in drawers beneath the cases in which the corresponding exhibited portion is placed. This applies principally to the fossil specimens, the shells, and the minerals. The reserve birds and insects have special rooms devoted to them, and the extensive series of reptiles, fishes, and other animals preserved in spirit is kept, for the purpose of safety, in a separate building behind the Museum. In the Botanical Department the reserve collections are kept in the well-known form of an Herbarium, or Hortus siccus.
Supplementary Collections.
The great bulk of the specimens being arranged in these three series, supplementary collections for facilitating the study of the distribution of animals and plants in space and in time would be advantageous. The first, constituting a geographical series, might show by illustrative examples the leading characteristics of the fauna and flora of each great region of the earth’s surface; the second, or palæontological series, would give examples of the fossil remains found most abundantly in each formation, arranged so far as may be in chronological order.
Geographical.
Geological.
The only attempt hitherto made at exhibiting a geographical series in the Museum is the collection of terrestrial and fresh-water vertebrated animals of the British Isles, arranged in the pavilion at the west end of the bird gallery. It would be difficult in the present building to find room for other geographical collections, however interesting and instructive. With regard to palæontological collections, although the specimens in the Department of Geology, so called, are mainly arranged not geologically, or according to stratigraphical position, but according to their natural affinities, yet, in many cases, it has been found convenient to adopt a mixed arrangement, the specimens within each large natural group being classified according to the sequence in age of the strata in which they were buried. Such an arrangement, however, is only applicable to the fossils of a particular region, owing to the difficulties in accurately determining the correspondence in age of formations occurring in distant parts of the earth’s surface; hence a large and varied palæontological collection, such as that of the British Museum, is best arranged in the main upon a systematic or zoological and botanical basis. A limited series showing the more characteristic British rock-formations with their included fossil remains, placed in chronological sequence, is arranged in one of the galleries of the Geological Department.