224 COMPARATIVE PHYSIOLOGY OF THE BRAIN 



5. Although I heartily sympathise with Bethe's re- 

 action against the anthropomorphic conception of 

 animal instincts, I yet believe that he is mistaken in 

 denying the existence of associative memory in ants 

 or bees. The fact that bees find their way home 

 through the air cannot depend upon any trace left in 

 their path. It can only depend upon memory and, as 

 I believe, upon visual memory. If the bee-hive be 

 removed while the bees have swarmed out, they will 

 return to and gather at the spot where the entrance 

 to the hive used to be. Bethe is not willing to admit 

 that this indicates the existence of a visual image of 

 memory of the locality of the nest, professing to con- 

 sider it possible that unknown forces guide the bee 

 reflexly. 



I have recently had a chance to observe the activity 

 of solitary wasps and have come to the conclusion 

 that these animals are guided back to their nest by 

 their memory. 



My observations were made on Ammophila, a spe- 

 cies of wasps, whose habits have been carefully stud- 

 ied and described by Mr. and Mrs. Peckham (7). 

 Ammophila makes a small hole in the ground and 

 then goes out to hunt for a caterpillar, which, when 

 found, it paralyses by one or several stings. The 

 wasp carries the caterpillar back to the nest, puts 

 it into the hole, and covers it with sand. Before this 

 is done, it deposits its egg and the caterpillar serves 

 the young larva as food. 



I will describe one observation on the means these 



