Hilgendokf. — Sense of Direction in Bees. 487 



this possible view of the case that I made the following 

 experiments. 



3. I here wished to disturb or annul the magnetic field 

 in which the bees usually lived, both on their outward and 

 homeward journey: to follow up my original illustration, to 

 obliterate all the tracks across the plain, and make only one 

 broad and distinct track, that would go wherever the man 

 went, and disappear immediately behind him. To do this I at- 

 tached a small powerfully magnetized needle to the back of the 

 thorax of the bee, carried him 100 yards away from his hive, 

 and liberated him. The attached magnet was sufficiently 

 strong to hold a small suspended magnet at right angles to 

 the lines of force of the earth's magnetism. The weight of 

 the attached magnet and the adhesive used was 40 milli- 

 grammes ; the average weight of the bees used was 120 milli- 

 grammes ; so that the load was one-third of the bee's own 

 weight. I used drone bees in this experiment, as they were 

 stronger, to carry the magnet, and as workers would have 

 injured themselves by using their stings during the fixing of 

 the magnet. I fastened the magnets to the bees in all direc- 

 tions — i.e., with the north pole pointing over their head, with 

 the south pole pointing over their head, and with the poles 

 pointing to left and right of the bees. About one-third of the 

 bees were unable to carry their burden, and fell into the grass 

 when liberated. These were not counted, only those that 

 flew into the air from my hand being included in the following 

 numbers : Bees liberated, 12 ; returned home, 8. Of the four 

 that were lost two were evidently weak on starting, and the 

 number that returned was large considering the disadvantages 

 they were flying under. 



This experiment answers the objection I supposed, and 

 makes it still more improbable that the bees find their way 

 home by magnetic sense, for this sense was in effect blind- 

 folded, both on their outward and return journeys, and still 

 they came home. The only other objection I can conceive is 

 this : Suppose the attached magnet were not strong enough to 

 completely obliterate the lines of force of the earth's magnetic 

 field, but only to distort them, then, since in the last experi- 

 ment the lines were distorted consistently equally on the 

 outward and homeward journey, the distortion might not 

 count for anything. A little consideration of the two former 

 experiments will prove that this objection is invalid, but with 

 a view to refuting it experimentally I made my last test. 



4. In this case I took the bees away from home in their 

 natural magnetic field. At 100 yards away I fastened to 

 them the magnet in all the three positions before mentioned, 

 and then liberated them : Bees liberated, 5 ; returned home, 3. 

 Thus in the third case also it appeared that the bees' power 



