XV 
THE RELATION OF FACTS TO THEORIES 
315 
This is in outline Simroth’s theory as to the 
origin of colour. His paper contains also numerous 
other suggestions which we cannot well discuss here. 
In general, he appears to believe that pigments are 
all related, that their development follows a definite 
order, and that their origin is due to the properties 
of protoplasm and the inherited stimuli of external 
conditions, such as light and warmth. On these, 
which he calls “ inorganic ” factors, he is inclined to 
lay much stress, especially in such cases as the 
colours of shells, in which he says there can be no 
question of adaptation. 
The theory is interesting in spite of its vagueness, 
and is included here because it is in many respects 
typical of recent theories. As neither it nor the 
other suggestions similarly based upon an inheritance 
of the effects of environmental stimuli, have the ex¬ 
tensive following possessed by the Natural Selectionist 
theory, we shall return, before going further, to a 
detailed discussion of the latter, beginning with the 
familiar subject of mimicry. 
Criticism of Natural Selection 
The existence of colour resemblances between 
widely separated organisms, and that explanation 
of it which is implicit in the term Mimicry, have 
recently become almost universally familiar. The 
term in its present use was first employed by Mr. 
Bates, and his suggestions were adopted by Darwin, 
Wallace, and others, and have since been widely 
accepted. Criticism has, however, never been want¬ 
ing, and in a recent paper M. M. C. Piepers brings 
