70 



THE EYE IN EVOLUTION 



taken to be an example of the light-compass reaction, but the response 

 could be equally explained by orientation by the j^attern of polarization 

 which also shifts with the sun (Griffin, 1953 ; Wellington, 1955). The 

 homing of the honey-bee when dejirived of other optical clues such as 

 conspicuous landmarks^ is determined by the same mechanism (Wolf, 

 1927 ; von Frisch, 1931). Behavioural experiments have demonstrated 

 that certain insects are not only able to analyse the polarization of 

 light but can retain its pattern in their memory to take account of the 

 alteration in the position of the sun with the time of day (von Frisch, 

 1950 ; Vowles, 1950 ; Griffin, 1950 ; Stephens et al., 1952) ; by this 

 type of mnemotaxis it is probable that homing remains accurate for 

 long journeys despite the changing position of the sun. 



It is not to be thought, however, that the homing of the ant need be an 

 entirely visual process. Bonnet (1779-83) first showed that odour trails may 

 be an effective aid (Carthy, 1950 ; Vowles, 1955), and the ability of this insect 

 to improve its path-finding and avoid detours is exemplified in its extraordinary 

 capacity to learn quite complex mazes (Turner, 1907 ; Schneirla, 1929-33 ; etc.). 



It is interesting that the " danciyig " of bees, the ballet by which 

 they communicate to other foraging bees the direction, the distance and 

 the richness of a discovery of nectar, is also largely determined by the 



J I ' I 



j^ 



I 1 

 / ; 





Fig. 45. — The Dance-figures of Bees. 



(a) The round dance for short distances performed by German and 



Austrian bees, (b) The " sickle dance " for short distances performed by 



Dutch and Swiss bees, (c) The figure-of-eight dance for long distances, with 



the " wagi.:'. '-run " forming the central component of the figure (von Frisch). 



1 p. 78. 



