EECOGXITIOX-MAEKS 181 



Recognition hy Butterflies 



This case shows how easy it is to make mistakes or arrive 

 at wrong conchisions, imless we take account of all the de- 

 tails of a problem, and endeavour to follow out the exact proc- 

 esses of nature by the help of facts known to us. I can 

 say this with more confidence, because I find that I have 

 myself come to a hasty conclusion, which I now see to be er- 

 roneous, on one aspect of this very question ; and as it in- 

 volves a problem of some importance I will here state what it 

 is. I find that in all my writings on this subject I have as- 

 sumed, without going into details, that the theory of ^^ recog- 

 nition-marks," which so well accounts for a very widespread 

 type of marking and coloration in birds and mammals, is also 

 applicable to a large portion of the markings of insects, es- 

 pecially in the case of butterflies. But a little consideration 

 shows that there is no resemblance between the two cases. 

 Young mammals and birds grow up with their parents, and 

 get to know their appearance in every detail. They also 

 have usually brothers and sisters growing up with them, so 

 that by the time they go out into the w^orld to care for them- 

 selves they are thoroughly acquainted with the difference be- 

 tween themselves and other species, even those nearly allied 

 to them. This complete knowledge is increased by the fact 

 that they are able, through the mobility of the head and neck, 

 to see almost every part of their own bodies, and thus know 

 that they themselves do resemble their parents. 



But with the butterflies, and most other insects, everything 

 is different. The caterpillar never knows its parent, and when 

 the butterfly emerges from the pupa and takes flight, it seems 

 quite impossible that, among the numerous butterflies of all 

 sizes, shapes, and colours that it may immediately encounter, 

 it can possibly know, h^j sight, which are of its own race. Tt 

 must be remembered that from tlie position nf its eyes if 

 cannot see itself except at so oblique an angle as to be al- 

 most useless; and when we consider the extreme diversity of 



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