172 
COLOURS AND COLORATION IN ANIMALS. 
Aug., 1892. 
numerous examples drawn from all sources, of the principal 
facts and orthodox theories which have been touched upon 
above, but also brings forward facts new or not generally 
known, and champions some unorthodox theories as to the 
origin of colour changes. The book has grown out of 
materials used by him for the “Davis Lectures,” delivered 
in the Zoological Society’s Gardens in 1890, and is 
“ addressed to persons having no special knowledge of 
zoology.” While the book does not claim to contain 
much that is quite new, yet certain facts and theories 
are in it, for the first time, brought before the general 
public out of the obscurity of periodicals, many of 
which are foreign; an important feature being that the 
action of other agents than natural selection in modifying 
colours is taken into account. Most writers on the subject 
consider colour to be of use to its owner only in one of the 
ways mentioned above, and to have been developed by natural 
or sexual selection ; Mr. Beddard shows good reason for 
differing to some extent from these widely received generali¬ 
sations. He shows that colours may serve other purposes 
than those mentioned; that what to human eyes seem to be 
excellent modes of concealment, may not be so to the eyes of 
lower animals ; that cases of resemblance between animals 
may not be due to mimicry, and that there may be other 
agents than natural or sexual selection engaged in developing 
colours. These points must now be dealt with in a little 
more detail. 
In considering the subject, Mr. Beddard points out that 
we must draw one very important distinction, that between the 
colours and coloration of animals : colours, that is the actual 
tints (blue, red, etc.), found in animals are a normal product 
of the organisation entirely independent of utility ; they are 
due either to the structure of the surface on which they 
appear or. to the molecular constitution of pigments present 
in the animal, and are, therefore, optical effects due to purely 
physical causes, and per se are of no use to the animal. On 
the other hand, the arrangement and distribution of colours, 
or coloration, may be of great importance to an animal, and 
may be developed and modified by natural or sexual selection, 
and probably by other agents. Colour, then, is a purely 
physical property; it is due, principally, to the presence of 
pigment, for even where largely caused by structure, pig¬ 
ment is generally present, forming a background, without 
which the colour is not visible. Pigment, therefore, is largely 
concerned in the production of colour, and the origin of a 
given pigment may explain the meaning of coloration. 
