ANIMAL SENSE PERCEPTIONS-. 323 



disposal was restricted to a few badly preserved specimens."* 

 The importance of a clear comprehension of animal sense cog- 

 nitions when a theory like that of mimicry is propounded must be 

 obvious. Take, for instance, a bird and a protectively coloured 

 caterpillar, such as it appears to our cognitions. Should the 

 power of vision in the bird be in excess of that possessed by our- 

 selves, the resemblance may be only superficial and powerless ; 

 should it be less, then the protection may be excessive — an idea 

 almost unthinkable in the light of the doctrine of natural selec- 

 tion. We may see what appears to be, and may be, wonderful 

 assimilative colouration or mimicking disguise, 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 

 power of hearing, of which we know less. We certainly do not 

 hear a tithe of the sounds produced by insects ; the effect of 

 some stridulating organs we can only comparatively estimate by 

 their structural affinities to others of a more developed character, 

 and which produce sounds capable of being recognized by our 

 own sense of hearing. It is probable that many insect enemies 

 discover their prey by sound alone. f Other creatures find their 

 food without apparently either sight or hearing. According to 

 Jonathan Couch, the common Sea-hog or Sea-egg {Echinus escu- 

 lenius), "though apparently destitute of every sense, or possibility 

 of regarding external objects by sight or hearing,! will travel up 



* ' Essays upon Heredity, &c.' Eng. transl. vol. ii. p. 9. 



t " It is of course possible, if not probable, that Ants, even if deaf to 

 sounds which we hear, may hear others to which we are deaf " (Lord Avebury 

 (Sir John Lubbock), ' Ants, Bees, and Wasps,' p. 223). — " There are sounds 

 which we cannot hear, there are sights which the eye cannot see. But 

 besides all these there must be countless aspects of external nature of which 

 we have no knowledge ; of which, owing to the absence of appropriate 

 organs, we can form no conception ; which imagination cannot picture, nor 

 language express" (Balfour, 'Foundations of Belief,' p. 69). — On the other 

 hand, Mr. Pocock asserts that "there is not a particle of evidence that 

 either the large Spiders or the Scorpions can hear the sounds that their own 

 stridulating organs emit" (' Natural Science,' vol. ix. p. 24). — Mr. Edmund 

 Selous inclines to the view that " thought transference " occurs among birds 

 ('Bird Watching,' p. 219 etseq.). 



I By experiment, Romanes found " the Echini manifesting a strong dis- 

 position to crawl towards, and remain in, the light " (' Jelly-Fish, Star-Fish, 

 and Sea-Urchins,' p. 319). 



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