30 ANIMAL INTELLIGENCE. 



mistakable evidence of consciousness and intelligence. 

 This observer had an opportunity of watching them for a 

 long time in the zoological station at Naples ; and he 

 says that they appeared to recognise their keeper after 

 they had for some time received their food from him. 

 Hollmann narrates that an octopus, which had had a 

 struggle with a lobster, followed the latter into an adjacent 

 tank, to which it had been removed for safety, and there 

 destroyed it. In order to do this the octopus had to 

 climb up a vertical partition above the surface of the 

 water and descend the other side.^ According to 

 Schneider, the Cephalopoda have an abstract idea of 

 water, seeking to return to it when removed, even though 

 they do not see it. But this probably arises from the 

 sense of discomfort due to exposure of their skin to the 

 air ; and if we can call it an ' idea,' it is doubtless shared, 

 by all other aquatic MoUusca when exposed to air. 



* Lehen der Cephalo^odenj s. 21. 



