ANIMAL SENSE PERCEPTIONS. 329 



invariabh' selects and visits a flower of one particular colour, we 

 can only record the observation, but certainly not assume that 

 what we see as white is seen by them in the same hue. Mr. J. 

 A. Harvie-Brown has protested against the assumption " that 

 the colour of insects, as seen by us, is comparable with what may 

 be seen by fish. Fish see though a different medium from ours, 

 and surely we see differently through theirs."* Prof. Plateau, 

 an authority on the physiology of Arthropods, a few years ago 

 published a series of memoirs giving the results of his experi- 

 ments in endeavouring to ascertain the actual powers of vision 

 possessed by insects and other Arthropods. f Dr. Sharp, of 

 Cambridge, has placed us all under an obligation by giving a 

 condensed account of these observations, and also a critical 

 summary of results. He gives his general impressions as derived 

 from Plateau's experiments as follows : — 



*' 1. Insects in motion are guided largely by the direction of 

 light, and the existence of lights and shades. That when walk- 

 ing they are guided by a combination of light-impressions, with 

 specific habit (that is, going upwards or downwards, towards 

 the light, or away from the light), and by tactile impressions; 

 these latter not acting when the insect is in flight. 



" 2. That there is at present no evidence at all that the light 

 perceptions are sufficiently complex to be entitled to be called 

 seeing ; but that, as the large development of the compound eye 

 permits the simultaneous perception of movement, its direction, 

 and of lights and shades over a certain area, a Dragonfly may 

 pursue and capture another insect without seeing it in our sense 

 of the word seeing." t 



Before leaving this section of our subject, and to make clear 

 our suggestion that little can be justly predicated as to sight 

 preferences or warnings by insects, we may again quote Mr. G, 



* ' The Wonderful Trout,' p. 42. 



t ' BuU. de I'Acad. Eoy. de Belgique,' 1887, 1888. 



I ' Trans. Ent. Soc' 1889, pp. 407-8. 

 Dr. Sharp has elsewhere described the compound or faceted eyes of 

 insects as being " totally different in structure and very distinct in function 

 from the ej^es of Vertebrata, and are seated on very large special lobes of the 

 brain, which indeed are so large and so complex in structure that insects may 

 be described as possessing special ocular brains brought into relation with the 

 lights, shades, and movements of the external world by a remarkably com- 

 plex optical apparatus " (' Cambr. Nat. Hist.' vol. v. p. 98). 



