21 7 
view. Consequently there is no universal instinctive shrink 
ing from conspicuous colour on the part of the enemy. 
It is false to say that certain disabilities will not deter 
from attack apart from warning colours. It is not certain 
that if an insect were attacked and rejected that it would 
therefore perish. It is not true that certain disabilities as 
sociated with conspicuous colours deter from attack. How 
far the animals so endowed are liable to attack depends 
upon the pressure of necessity due to hunger or to skill 
in overcoming disabilities on the part of the insect-eater. 
Nor is the explanation of the way in which warning 
colours have been produced by Natural Selection more 
satisfactory. Starting with an edible species which has 
not a particularly conspicuous colouring, it is assumed 
that there is first an evolution of a nauseous taste or 
other disability, and secondly an evolution of warning 
colours. Mr. Wallace gives two different explanations of 
the way in which a nauseous taste was developed. In 
his Tropical Nature, he speaks of the time when “ the 
Danaidae first began to acquire those nauseous secretions, 
which are their protection in the early stages of their 
development ” ; and then of another time when they be 
came decidedly unpalatable.* In his Darwinism, he says, 
“ The Heliconidae first arose from some ancestral species 
or group which, owing to the food of the larvie or some 
other cause, possessed disagreeable juices that caused them 
to be disliked by the usual enemies of their kind.”j- 
If the nauseous taste were the result of the direct action 
of the adoption of some new food-plant, one of two results 
would follow. Either the enemy would leave the insect 
severely alone, having plenty of other food to resort to ; 
and then, in the absence of any interposition on the part 
p. 190. 
t p. 243.