VII 
THE COLOURS OF THE LEPIDOPTERA 
147 
of variable coloration, or the nature of the adjust¬ 
ments by which it is rendered possible. Those who 
are interested in the question will find it discussed 
in numerous other popular books besides those 
already mentioned. It is, however, of some interest 
for our purpose to note that, according to recent 
research, it is not so much the colour of the environ¬ 
ment which directly affects the larvze as the intensity 
of the light (see Garbowski). In other respects also 
some of the first crude statements made on the 
subject are being modified. It may, indeed, be 
accepted as a general truth in biology that when¬ 
ever a series of phenomena seem to be susceptible 
of an extremely simple and beautiful explanation, 
that explanation is wrong and founded on an im¬ 
perfect acquaintance with the phenomena in ques¬ 
tion. All recent progress in biological theory has 
shown that life is not simple but complex, and has 
involved a substitution of extremely complex theories 
for simple ones. 
The Colours of Butterflies 
In butterflies the colour-phenomena are much 
more complex than in caterpillars, for while in the 
latter the colour is a direct pigmental effect, in the 
former the two factors of structure and pigment occur 
in combination. In both kinds of colour in butter¬ 
flies the important elements are the scales of the 
wings. These are outgrowths of the chitinous 
cuticle, and consist of a double membrane ; the outer 
membrane is frequently much differentiated, and 
may display rows of blunt projections, which are 
