

Distance of 





400 meters. 



1. 



5 



min 



2. 



7 



min 



3, 



4. 10 



min 



5-8. ? 



min 





Distance of 





650 meters. 



1. 



4:% min. 



2. 



5^4 min. 



3. 



5}4 min. 



4. 



7% min. 



5. 



9 min. 



6, 



7. IOI/2 min. 



8. 



I min. 



22 Natural History of the Honeybee. 



on a quiet sunny day at distances of 350, 400, and 650 meters from the hive. The result 

 is as follows, from an observation of twelve minutes at the hive entrance: 



Distance of 

 350 meters. 



1. iy 2 min. 



2. 2% min. 

 ; j3. 2 1 / 4 min. 



: 4. 2^4 min. 



5. 2% min. 



6. 3% min. 



This time experiment alone proves that there can be no explanation for an "unknown 

 force" which "draws to the hive like a magnet;" for if it really existed these great 

 differences in time would be entirely inexplicable. Since there was no wind, and the 

 sun was shining, there were no hindrances to flight, and the bees ought to have reached 

 the hive-entrance in the shortest period and at the same time. Further, supposing the 

 existence of an unknown force which draws bees back to the hive directly, the length 

 of time for flight is in itself too long, because bees fly very quickly. A carrier pigeon 

 would undoubtedly cover the same distance in question under the same favorable con- 

 ditions in eighteen, twenty-four, and thirty-nine seconds, if we use as proof the calcula- 

 tions of Ziegler on the swiftness of carrier pigeons.* 7 Their flight is found to be often 

 as swift as 1000 meters per minute. If we now take the flight of bees to be half that, 

 500 meters per minute (a velocity which has been directly observed by Cowan es ) then 

 the ' ' unknown force ' 'should have led the bees back in thirty-six, forty-eight, and seventy- 

 eight seconds. If we double the time because the bees in the experiment were carrying 

 honey, 00 the time would be normally about one minute! twelve seconds, one minute 

 thirty-six seconds, and two minutes thirty-six seconds. Comparing this with Bethe 's 

 table we find a striking difference which is unintelligible if we accept thq idea of the 

 "unknown force," but this difference is easily explained if we consider that the bees 

 had to orient themselves with their eyes, and that they at first made errors in direction 

 so that they found the hive singly after three and one-half, ten, and ten and one-half 

 minutes had elapsed. 



Of the nineteen bees which were let fly from a courtyard into the street, Bethe observed 

 that seventeen of them ("at about half the height of the houses," "before they flew as 

 high as the roof") "took the exact direction" for the hives at the Institute. That these 

 bees probably followed only light stimuli in taking this direction I have said before, 

 for that they really did not return directly to the hive is shown by the above table. 

 If all the bees, ' ' almost without exception, ' ' which were set free in an " unknown neigh- 

 borhood" under the conditions cited, took "exactly the right direction" they would 

 have come in very much more quickly. 70 I would here refer further to what I inci- 

 dentally work out from the box experiment (see p. 25). 



The "unknown force" does not lead the bees back to the hive, but, Bethe suggests, 

 to the place where the hive stands or has usually stood. Is not this memory of location? 

 What does Bethe understand by the "unknown force"? We receive no explanation. 

 He thinks it is a power lying outside the bees which draws them to this place in 

 space as a magnet draws steel" (Bethe, p. 93). He^ has made no investigations to find 

 out whether this unknown force is connected at all with any organ of the bee. 



But we shall attempt to get nearer to this mysterious power. 



67 H. E. Ziegler, Die Geschwindigkeit der Brieftauben, Zoolog. Jahrb., X. Bd., 1897. 



^Thos. Wm. Cowan, The Honey-bee, its Natural History, Anatomy, and Physiology." London, 1890: 

 German edition, Braunschweig, 1891. 



""One can not take any bees at all for this experiment; but such as come into the hive laden must 

 be chosen, for otherwise we have no guarantee that the bees will come home by (he shortest wav and 

 not go foraging first." Bethe, 1. c, p. 87. 



70 The assertion that beesf would fly directly to the hive, but that on the way they alighted at any 

 time, then flew again in the direct line, is in contradiction to the habits of tees. They flv many 

 kilometers without resting. 



