THE SOCIAL INSECTS 



taken to show that the dances which the marked bees have 

 been seen to perform have told other bees in the hive of the 

 distance (and as will be shown in a moment) also the direction 

 of the distant source. Thus until some bees have had time 

 to convey information to the hive about the nearer source, 

 the more distant one is much more visited. The number of 

 visits to a source depends at first on distance but afterwards 

 on whether the hive has been told about it. When told where 

 to go, workers find a source much more quickly than they 

 do by random searching. 



The most extraordinary of von Frisch's discoveries was 

 of the method by which bees indicate the direction of a 

 source of food. The workers returning from a source may 

 perform the dance on the horizontal alighting board just 

 outside the hive. This is fully exposed to daylight and under 

 those circumstances the straight part of the track of the tail- 

 wagging dance points towards the source of food. With the 

 round dance, the direction is not indicated, as far as is known. 

 However, both dances are usually done in the dark, inside 

 the hive, on a comb which is vertical. In this case, the vertical 

 straight run of the tail-wagging dance indicates that the 

 source is on the imaginary straight line connecting the hive 

 with the sun. If on the straight run the bee moves upwards. 

 the source is towards the sun, if downwards away from it, 

 If the straight run is at an angle to the right or the left of the 

 vertical, the source is at the same angle to the direction of 

 the sun. This behaviour was observed in numbers of marked 

 bees collecting food from known artificial sources placed in 

 different positions relative to the hive and the sun. The 

 direction of the dance varies somewhat on each occasion the 

 straight run is made, and the average direction varies to some 

 extent in different workers, and at different times of the day. 

 In one experiment in which the direction of the dance was 



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