THE THEORY OF MIMICRY 141 



One of the weak points in the mimicry theory is that it 

 depends almost exclusively on vision for its elucidation, 

 and it further relies upon the sight of the lov^'er animals 

 being of the same nature and capacity as that of the 

 human eye. Next to nothing is knoAvn of the capacity 

 and comprehensiveness of the faceted eyes of insects, and 

 the sight of birds, although it doubtless varies much 

 inter se, is probably far keener and possibh^ less dis- 

 criminating than that of the human. The far ranging 

 eye of the vulture is a good illustration of this point. 

 Sight among insects and among the lower orders of ani- 

 mals generally is doubtless very subsidiary to their other 

 sense organs, the natures of some of which it is impos- 

 sible for us correctly to define. 



Since writing the above it has been my good fortune 

 to come across and read an excellent essay on " Animal 

 Sense Perceptions '' by Mr. AV. L. Distant contained in 

 "The Zoologist" of September, 1901. The subject is 

 treated fully and in the usual thorough style which one 

 expects from his ripe experience. I give the following 

 excerpts to show how he views the question (page 323) : 

 '^ The importance of a clear comprehension of ani- 

 mal sense cognitions when a theory like that of 

 miimicry is propounded must be obvious. Take, for 

 instance, a bird or protectively coloured caterpillar, 

 such as it appears to our cognitions. Should the 

 power of vision in the bird be in excess of that pos- 

 sessed by ourselves, the resemblance may be only 

 superficial and powerless ; should it be less, then the 

 protection may be excessive — an idea almost un- 

 thinkable in the light of the doctrine of natural 

 selection." 



" We may see w^hat appears to be, and may be, 

 w^onderful assimilative colouration or mimicking 

 disguises, but the creature so protected, as it appears 

 to us, may be readily detected by a keenness of scent 

 in its enemies, of which we know little, or by a paw^r 

 of hearing, of w^hich we know less." 



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