THE WAYS OF LIFE 235 



tion ', more or less comparable to that of carrier pigeons, 

 and located in the cerebral ganglia. 



The Peckhams made some fine experiments on ' homing ' 

 in social wasps. For instance, they captured a number of 

 wasps leaving the nest in the morning, and, having stopped 

 up the nest, took them to some distance off. The first lot 

 was liberated a furlong out on a lake ; the second in a barn 

 with a window at each end one towards, the other away 

 from the nest ; the third, three hundred yards away in 

 the country. From fifty to seventy per cent, returned to 

 the nest. It seemed to the observers that the wasps rose 

 high in the air and flew about in circles until they saw 

 something they remembered. 



Some careful observations have been made on the 

 ' homing ' habit in limpets. In many cases, it has been 

 shown that particular limpets have particular sites on the 

 rock, and that they return to these after they have been 

 on a short excursion. They appear to have a topographical 

 memory, which fixes impressions not only of the particular 

 site but of its surroundings. The reason why it matters 

 that the limpet should ' go home ', is that the margin of 

 their shell grows so as to fit the little inequalities on the 

 surface of the rock, and a small amount of water is thus 

 retained during the period when they are left dry by the 

 retreating tide. Lloyd Morgan found that of twenty-one 

 limpets moved for eighteen inches, eighteen found their 

 way back ; of thirty-six moved for twenty-four inches, 

 only five got home again. 



' Masking '. Various crabs, such as the common 

 Hyas araneus, fasten seaweed on to their carapace, and 

 thus cover themselves with effective disguise. When they 

 put on an inconveniently large piece, they take it off again 



