24 
CENTRAL HALL. 
Group illus- 
trating 
Albinism. 
Group illus- 
trating 
Melanism. 
Case illustrat- 
ing Protective 
Resemblances 
and Mimicry. 
of colour in different individuals. As many as twenty-tliree 
specimens are shown in the case, no two being entirely alike. 
The next case contains a series of specimens illustrating a^&^7^^sm,, 
a condition in which the pigment or colouring matter, usually 
present in the tissues constituting the external covering of the 
body, and which gives them their characteristic hue, is absent. 
Individuals in this condition occur among many animals of 
various kinds, and are called " albinos." In some of the speci- 
mens shown in the case the albinism is complete, but in many 
it is partial, the absence of colouring matter being limited to 
portions of the surface only. 
A fourth case shows examples of the opposite condition, 
called melanism, depending upon an excess of dark-coloured 
pigment in the skin and its appendages, the hair, feathers, etc., 
beyond what is normally met with in the species. This is by 
no means so frequent as albinism, A black Leopard in the 
middle of the case is a good illustration. It is not a distinct 
species, but an individual variety of the common Leopard, born 
from parents of the normal colour. A black Bullfinch is intro- 
duced as an example of acquired melanism, the bird having 
turned black in captivity. 
The case nearest the great staircase contains examples of a 
subject attracting much attention among naturalists at the 
present time — Protective Kesemblances and Mimicry. The 
simplest form, that of conformity of general style of colouring to 
surrounding conditions, is seen in the group at the bottom of the 
case, consisting of some of the commoner birds, mammals, and 
reptiles of the Egyptian desert, placed upon the stones and sand 
amid which they habitually live. The advantage of this colouring 
in concealing the herbivorous species from their enemies, and 
enabling the carnivorous to approach their prey unperceived, is 
obvious. Many excellent cases of concealment by adaptation to 
environment, especially in eggs and young birds, may be seen 
among the groups in the bird gallery. 
More special modifications for the same purpose are shown in 
the examples in the upper part of the case, of insects which closely 
resemble the inanimate objects, as leaves, twigs, &c., among which 
they dwell. The close imitation of a dead leaf, presented by 
the butterfly {Kallima inachis), when its wings are closed, could 
