CONSCIOUS PROTECTIVE RESEMBLANCE. 553 



and other di- or poly-morphism in the different individuals of the same 

 species. A single instance will make this clear. There are certain 

 genera of butterflies, such as Dismorphia (in the wide sense), Pseud- 

 acvaa, and Hypolimnas (also in the wide sense), of which almost the 

 whole of the numerous species are mimetic. Within the limits of each 

 genus the most divergent models have been followed, so that utterly 

 different colours and patterns have been produced in forms which are 

 still closely related, and in other structural features exhibit no corre- 

 sponding differences. In the most extreme case known to me, immense 

 differences occur in the different races of a form which systematists 

 consider as a single species, viz. Hypolimnas bolina. If we compare 

 the Indian form of female with those of the Malayan region, Australia, 

 and Polynesia, including Fiji (in which the local race itself con- 

 tains the most widely divergent forms), and remember that no corre- 

 sponding differences exist which would justify us in conferring specific 

 rank in any of the cases, we are driven to the conclusion that colour 

 and pattern are the most superficial of all specific characters, — of all 

 the least likely to persist unchanged when the models upon which they 

 were founded have long since disappeared. 



In one special case which I have observed, there is evidence that 

 changes in the nervous system have outlasted the markings which once 

 gave a meaning to them. Some of the remarkable larvae of the genus 

 Ophideres have two eye-spots at the junction of the anterior and middle 

 third of the body. They have the instinct of bending the anterior 

 third so that it rests under the middle one, and thus the eye-spots are 

 brought into an appropriate position apparently at the anterior end of 

 a somewhat snake-like body. But a caterpillar of this genus which I 

 found in Teneriffe assumed the attitude, on irritation, although the 

 eye-spots were almost completely wanting. 



11 It is worth considering whether the Miillerian principle may have 

 been operative in this case. 



12 Of course, no natural selectionist has ever been so unreasonable 

 as to contend for absolute protection. In every species, whether 

 defended by the most distasteful or dangerous qualities, or the most 

 effective concealment, no more can be achieved than to keep up the 

 average numbers under average conditions, and this means that an 

 immense majority of individuals are doomed to failure. As regards 

 concealment, success merely means that enemies have so far to work 

 for their living that in the time at their disposal they cannot do more 

 than reduce the number of individuals to the average. Warning 

 colours and unpalatable or otherwise unpleasant qualities are more 

 complex as a means of defence, depending as they do for their success 

 upon the co-existence of other nnre desirable food. Their operation, 



