THE HOMING OF THE BURROWING-BEES. 257 



of flight bore any constant relation either to the direction of the 

 wind or to the rays of the sun. Many of the nests observed by 

 me were in the sunshine a part of the day and in shadow the 

 balance of the day, yet the bee found the nest just as readily 

 when it was in the shadow as it did when it was in bright sunlight. 



Any pronounced change made in the topography of the vicin- 

 ity of the nest, while the bee is away from its burrow, is sure to 

 cause the insect, on its return, to be forced to search about in 

 order to find the entrance to its home [Ex. i, 3, 4, 10, 14, I., 

 II., IV., V.]. This is true even when the nest opening is in full 

 view [Ex. I, 3, I., II.]. If the proper alterations are made in 

 the topography of the vicinity of the nest, the bee may be induced 

 to enter, temporarily, a false burrow [Ex. 4, I., II., IV., V.]. 

 A bee that has not been experimented upon is much more 

 affected by slight alterations made in the topography of the vicin- 

 ity of the burrow than is the same bee after a prolonged period 

 of experimentation [cf Ex. i with Ex. 13 and 14]. All of these 

 statements militate against the old idea of a "homing instinct," 

 against Pieron's kinesthetic reflex hypothesis and against Bethe's 

 contention that bees are guided home by an unknown force which 

 acts reflexly ; for if either of these assumptions were true, changes 

 made in the topography of the vicinity of the nest should not 

 alter the behavior of the bees. 



It would be erroneous to claim that these burrowing-bees find 

 their way home by the method of " trial and error," for there is 

 no gradual " stamping in " of an appropriate response. When 

 the bee, on returning home, finds the environment markedly 

 changed, it searches until the opening of the burrow is found. 

 Before departing again for the field, the bee makes a careful 

 examination of the vicinity of the nest [Ex. i, 3, 4, 13, IV., V.]. 

 On its next return to the burrow, unless the environment has 

 been changed in the meanwhile, the bee flies directly to the 

 burrow in the minimal amount of time ; there is none of that 

 blundering into a solution which the method of "trial and error" 

 demands [Ex. 2, 5, VI.]. 



By a process of elimination, the most consistent explanation 

 of the above behavior is the assumption that burrowing-bees 

 utilize memory in finding the way home, and that they examine 



